Search results

Title: Improvement of Quality Prediction in Inter-Connected Manufacturing System by Integrating Multi-Source Data.
Creator: Ren, Jie, Wang, Hui, Vanli, Omer Arda, Park, Chiwoo, Huffer, Fred W. (Fred William), Florida State University, FAMU-FSU College of Engineering, Department of Industrial and...
Show moreRen, Jie, Wang, Hui, Vanli, Omer Arda, Park, Chiwoo, Huffer, Fred W. (Fred William), Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: With the development of advanced sensing and network technology such as wireless data transmission and data storage and analytics under cloud platforms, the manufacturing plant is going through a new revolution, by which different production units/components can communicate with each other, leading to inter-connected manufacturing. The interconnection enables the close coordination of process control actions among machines to improve product quality. Traditional quality prediction methods...
Show moreWith the development of advanced sensing and network technology such as wireless data transmission and data storage and analytics under cloud platforms, the manufacturing plant is going through a new revolution, by which different production units/components can communicate with each other, leading to inter-connected manufacturing. The interconnection enables the close coordination of process control actions among machines to improve product quality. Traditional quality prediction methods that focus on the data from one single source are not sufficient to deal with the variation modeling, and quality prediction problems involved the inter-connected manufacturing. Instead, new quality prediction methods that can integrate the data from multiple sources are necessary. This research addresses the fundamental challenges in improving quality prediction by data fusion for inter-connected manufacturing including knowledge sharing and transfer among different machines and collaboration error monitoring. The methodology is demonstrated through surface machining and additive manufacturing processes. The first study is on the surface quality prediction for one machining process by fusing multi-resolution spatial data measured from multiple surfaces or different surface machining processes. The surface variation is decomposed into a global trend part that characterizes the spatially varying relationship of selected process variables and surface height and a zero-mean spatial Gaussian process part. Three models including two varying coefficient-based spatial models and an inference rule-based spatial model are proposed and compared. Also, transfer learning technique is used to help train the model via transferring useful information from a data-rich surface to a data-lacking surface, which demonstrates the advantage of inter-connected manufacturing. The second study deals with the surface mating errors caused by the surface variations from two inter-connected surface machining processes. A model aggregating data from two surfaces is proposed to predict the leak areas for surface assembly. By using the measurements of leak areas and the profiles of surfaces mated as training data along with Hagen–Poiseuille law, this study develops a novel diagnostic method to predict potential leak areas (leakage paths). The effectiveness and robustness of the proposed method are verified by an experiment and a simulation study. The approach provides practical guidance for the subsequent assembly process as well as troubleshooting in manufacturing processes. The last study focuses on the learning of quality prediction model in inter-connected additive manufacturing systems, by which different 3D printing processes involved are driven by similar printing mechanisms and can exchange quality data via a network. A quality prediction model that estimates the printing widths along the printing paths for material-extrusion-based additive manufacturing (a.k.a., fused filament fabrication or fused deposition modeling) is established by leveraging the between-printer quality data. The established mathematical model quantifies the printing line-width along the printing paths based on the kinematic parameters, e.g., printing speed and acceleration while considering data from multiple printers that contain between-machines similarity. The method can allow for the between-printer knowledge sharing to improve the quality prediction so that a printing process with limited historical data can quickly learn an effective quality model without intensive re-training, thus improving the system responsiveness to product variety. In the long run, the outcome of this research can help contribute to the development of high-efficient Internet-of-Things manufacturing services for personalized products.
Show less
Date Issued: 2019
Identifier: 2019_Spring_Ren_fsu_0071E_15160
Format: Thesis

Title: Heterogeneous Data Fusion for Performance Improvement in Electric Power Systems.
Creator: Gilanifar, Mostafa, Wang, Hui, Moses, Ren, Ozguven, Eren Erman, Park, Chiwoo, Vanli, Omer Arda, Florida State University, FAMU-FSU College of Engineering, Department of...
Show moreGilanifar, Mostafa, Wang, Hui, Moses, Ren, Ozguven, Eren Erman, Park, Chiwoo, Vanli, Omer Arda, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: The performance of the electric power system determines the cost-effective and reliable energy supply to maintain operations in a city. Electric power system performance improvement is important for utility companies in different aspects from maintenance and reliability to the environment. In a modern city, new monitoring devices are deployed to collect data in the electric power system and other city systems such as transportation. The heterogeneous data collected by new monitoring devices...
Show moreThe performance of the electric power system determines the cost-effective and reliable energy supply to maintain operations in a city. Electric power system performance improvement is important for utility companies in different aspects from maintenance and reliability to the environment. In a modern city, new monitoring devices are deployed to collect data in the electric power system and other city systems such as transportation. The heterogeneous data collected by new monitoring devices reveal the multi-community interactions in the electric power system and also reveal the interdependencies between different city systems such as electric power system and transportation system. This dissertation research studied the development of data fusion and multi-task learning algorithms in improving short-term load forecasting, fault detection, and rare faulty event detection by leveraging heterogeneous and multi-community data. The theoretical contribution of this study lies in the method selection and comparison for fusing transportation and electricity consumption data, and new methods of capturing between-community relatedness in guiding the knowledge transfer for the learning of Bayesian spatiotemporal Gaussian Process model, fault classification, and semi-supervised learning so that the performance of these algorithms are not limited by the specificity in the dataset and can reduce overfitting issues. The first study aims to forecast the electric load consumption and traffic counts accurately which benefits from the data fusion techniques in order to fill the lack of sufficient data. Accurate forecasting is mostly dependent on sufficient and reliable data. Traditional data collection methods may be necessary but not sufficient due to their limited coverage and expensive cost of implementation and maintenance. The advances in sensor networks and recent technological developments emerge a new opportunity. Specifically, data fusion tools can be used for improving the limited resolution in the data due to limitations on time frame, cost, accuracy, and reliability. In this study, a Bayesian spatiotemporal Gaussian Process model is proposed which employs the most informative spatiotemporal interdependency among its system, and covariates from other city systems. Results obtained from real-world data from the City of Tallahassee in Florida show that the multi-network data fusion framework improves the accuracy of load forecasting, and the proposed model outperforms all the existing methods. The second study is conducted for short-term electricity load forecasting for a residential community in a city which suffers from low-resolution data. Historically, extensive research has been conducted to improve the load forecasting accuracy using single-task machine learning methods, which rely on the information from one single data source. Such methods have limitations with low-resolution data from meters. Fusing the electricity consumption data from multiple communities can improve forecasting accuracy. Recently, an emerging family of machine learning algorithms, multi-task learning (MTL), have been developed and can be utilized for short-term load forecasting. However, appropriate modeling of the relatedness to enable the between-community knowledge transfer remains a challenge. This research proposes an improved MTL algorithm for a Bayesian spatiotemporal Gaussian process model (BSGP) to characterize the relatedness among the different communities in a city. It hypothesizes on the similar impacts of environmental and traffic conditions on electricity consumption in improving the accuracy of short-term electricity load forecasting. Furthermore, this study proposes a low ranked dirty model along with an iterative algorithm to improve the learning of model parameters under an MTL framework. This study used real-world data from two residential communities to demonstrate the proposed method through comparison with state-of-the-art methods. The third study investigates the fault (type) detection in power distribution systems by using the Distribution Phasor Measurement Unit (D-PMU) data. Historically, Traveling-wave and impedance-based methods are among the most notable fault detection techniques. The disadvantage of the impedance methods is that they rely on the knowledge of the network components characteristics. Although Traveling-wave methods have shown to be accurate, they require high-frequency measurements for reliable performance. Such high-resolution measurement data is expensive and may not be available all the times. More recently, D-PMU devices are used to observe better, record, and provide high-resolution voltage and current phasor measurements. In this study, a Multi-task Logistic Low-Ranked Dirty Model (MT-LLRDM) for fault detection is proposed to improve the accuracy by utilizing the similarities in the fault data streams among multiple locations across a power distribution network. The captured similarities supplement the information to the task of fault detection at a location of interest, creating a multi-task learning framework and thereby improving the learning accuracy. The algorithm is validated with real-time D-PMU streams from a hardware-in-the-loop testbed that emulates real field communication and monitoring conditions in distribution networks. Finally, a study is conducted for the fault (type) detection in power distribution systems when data suffers from the lack of labeled data. Supervised multi-task learning methods have limitations when there are a lot of missing data in the target domain especially records on fault data are lacking label. Labeled fault data can be very limited in the target community since fault data labeling is very time-consuming. Therefore, in this study, a multi-task semi-supervised learning method is proposed to simultaneously explore the latent structure in the unlabeled data to learn the labels and leverage the data from multiple locations in the power systems to improve the fault detection.
Show less
Date Issued: 2019
Identifier: 2019_Spring_Gilanifar_fsu_0071E_15164
Format: Thesis

Title: Manufacturing of Multimaterial Composites via Dual Robotic 3D Printing.
Creator: Frketic, Jolie Breaux, Dickens, Tarik, Clark, Jonathan E., Ramakrishnan, Subramanian, Liang, Zhiyong (Richard), Wang, Hui, Florida State University, FAMU-FSU College of...
Show moreFrketic, Jolie Breaux, Dickens, Tarik, Clark, Jonathan E., Ramakrishnan, Subramanian, Liang, Zhiyong (Richard), Wang, Hui, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Composite additive manufacturing (AM) is able to create products that have never before been able to be made. However, several processing and material setbacks keep AM from becoming the all-encompassing methodology for multifunctional printed composite parts. Current AM methods to create composites are focused on printing single materials, and while able to create complex parts quickly, have yet to leverage their full capability. To make strides towards an all-encompassing multi-material...
Show moreComposite additive manufacturing (AM) is able to create products that have never before been able to be made. However, several processing and material setbacks keep AM from becoming the all-encompassing methodology for multifunctional printed composite parts. Current AM methods to create composites are focused on printing single materials, and while able to create complex parts quickly, have yet to leverage their full capability. To make strides towards an all-encompassing multi-material additive manufacturing system, a collaborative dual selective compliance assembly robotic arm manufacturing system has been developed for cooperative additive manufacturing (CO-AM). The inclusion of cooperative robotic systems working simultaneously on a part while near each other spurs inquiry to the issues of effectiveness and practicality compared to what is witnessed in conventional operation. This research highlights our work on fundamentally understanding the process control-structure-property relationships of a novel mechatronic system for additive processing. The first study aims to narrate the design process and capabilities of this cooperative system, as well as measure current performance under typical operation. Investigations were aided with (1) computer vision analysis and (2) dynamic modeling to provide insight into the limitations of the current system. This study seeks to benchmark the performance of CO-AM as it compares to modern on market systems. The study shows that the CO-AM system can reach the same resolution as typical extrusion manufacturing devices. A time study found that a 36% reduction in time is able to be achieved in a non-optimized part, yielding an advantage over typical systems. A second study investigates the processing parameters (road overlap, speed, the time between extrusions, stepping and nozzle size) in CO-AM and how these process-property relationships can be used to create the strongest weld in the seam between two halves of a part printed collaboratively. From this study, it was found that the speed of printing, print overlap, and nozzle size were the most important in having a stronger weld. From these results, design rules and processing parameters for thermoplastic CO-AM were developed. Finally, a study was conducted to investigate the polymer welding and adhesion between adjoining printed roads. Theoretical studies have been used to determine how polymer-polymer welding at the interface between adjacent roads affects the strength between these printed interfaces. Micrographs of printed compact tension specimen interfaces were analyzed for thermoplastic welding. An image segmentation program was developed to elucidate the polymer diffusion and adhesion of printed parts and describes the strength of the printed part. It was found that a coefficient for weld entanglement is able to accurately depict the strength of a printed thermoplastic when an assumed strength along the weld is considered to be around 25% of the full strength of an injection molded part. This helps in further studies by enhancing the knowledge of the process-property relationship that is created when using additive manufacturing.
Show less
Date Issued: 2019
Identifier: 2019_Spring_Frketic_fsu_0071E_14912
Format: Thesis

Title: Scale-Up Sample Fabrication and Preliminary Transport Mechanism Study of Carbon Nanotube Based Electrical Conductor.
Creator: Zhang, Songlin, Liang, Zhiyong (Richard), Andrei, Petru, Zeng, Changchun (Chad), Dickens, Tarik, Florida State University, FAMU-FSU College of Engineering (Tallahassee, Fla.),...
Show moreZhang, Songlin, Liang, Zhiyong (Richard), Andrei, Petru, Zeng, Changchun (Chad), Dickens, Tarik, Florida State University, FAMU-FSU College of Engineering (Tallahassee, Fla.), Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Conductive materials are indispensable for almost all aspects of life. However, conventional metal conductors have some drawbacks including heavy weight and corrosion issues. Carbon nanotubes (CNTs) are promising as an alternative conductor that offers multiple advantages and functionalities including low density, corrosion resistance, and high specific mechanical/electrical/thermal properties. Much work has been done to improve the electrical conductivity of CNT assemblies, transferring the...
Show moreConductive materials are indispensable for almost all aspects of life. However, conventional metal conductors have some drawbacks including heavy weight and corrosion issues. Carbon nanotubes (CNTs) are promising as an alternative conductor that offers multiple advantages and functionalities including low density, corrosion resistance, and high specific mechanical/electrical/thermal properties. Much work has been done to improve the electrical conductivity of CNT assemblies, transferring the excellent properties of CNTs demonstrate at the nanoscale to practical applications such as fiber and films remains a challenge. This research focuses on studying the improvement of electrical/mechanical performance of CNT fibers/films. . Chapter 1 gives an introduction of CNT conductors. A comprehensive literature review of CNT conductor development is presented in Chapter 2. Chapters 3, 4 and 5 discuss three projects focuses on synergistic effects, interface design and scalable fabrication, respectively. Conclusions are given in Chapter 6. We attempted to improve the electrical conductivity of CNT films based on synergistic effects though alignment and chemical doping. We fabricated large-scale continuous CNT sheets with ultra-high and stable electrical conductivity, which reached a conductivity in the range of 104 S/cm. We also investigated the interface structural optimization between CNTs and carbon matrix to simultaneously enhance strength and conductivity. To achieve this, a unique interface enhancer, pyrolyzed polydopamine (py-PDA), was added between the CNTs and carbon matrix, which resulted in better load transfer and electron transport. The as-prepared CNT/py-PDA/C composite fibers demonstrated remarkable improvements in electrical conductivity (2.1 × 103 S/cm) and tensile strength (up to 727 MPa), which should prove to be advantageous comparing to previously reported CNT/C composites. We also studied and developed a roll-to-roll production capability to fabricate continuous nanotube sheets or buckypaper with relatively high and stable conductivity. The electrical conductivity of the resultant continuous buckypaper can be improved to 7.6 × 104 S/m by using an oxidant chemical (i.e. HNO3 and I2) doping method. Those results are valuable for seeking lightweight and flexible non-metal conductors for potential engineering applications.
Show less
Date Issued: 2019
Identifier: 2019_Summer_Zhang_fsu_0071E_15053
Format: Thesis

Title: Design and Fabrication of Carbon Nanotube-Based Multifunctional Composites and Advanced Sensors for Composites Manufacturing.
Creator: Nguyen, Nam Nhu, Liang, Zhiyong (Richard), Yeboah, Yaw D., Okoli, Okenwa O. I., Zeng, Changchun (Chad), Florida State University, FAMU-FSU College of Engineering (Tallahassee,...
Show moreNguyen, Nam Nhu, Liang, Zhiyong (Richard), Yeboah, Yaw D., Okoli, Okenwa O. I., Zeng, Changchun (Chad), Florida State University, FAMU-FSU College of Engineering (Tallahassee, Fla.), Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Polymer matrix composites are increasingly used in aerospace applications due to their high specific properties. Recently, wide application of composite materials leads to extensive research in improving manufacturing processes to increase production quality as well as potentially reduce cost. In addition, adding new functionality such as sensing, communication, lightning strike protection into composite structures to make multifunctional composites has gained more and more interests....
Show morePolymer matrix composites are increasingly used in aerospace applications due to their high specific properties. Recently, wide application of composite materials leads to extensive research in improving manufacturing processes to increase production quality as well as potentially reduce cost. In addition, adding new functionality such as sensing, communication, lightning strike protection into composite structures to make multifunctional composites has gained more and more interests. Incorporation of functionalities triggers the development of integration technologies as well as innovate manufacturing approaches such as 3D printing or additive manufacturing. In this research, the design and fabrication of multifunctional composites by using different techniques including in-situ curing, 3D printing, and printed sensor network on composite structures are studied. In-situ curing in CNT/CF hybrid composites is presented in this work as an effective technique to manufacture multifunctional composites. By passing electrical current through highly conductive CNT layers, composite is fully cured by heat generated from CNT layers. FEM simulation is used to demonstrate uniformity of composite temperature which was in good agreement with the experiment result. In addition, 3D printing of functional ink using graphite nanoplatelets and milled carbon fiber is discussed. We successfully formulated conductive ink with thermal conductivity of 2W/mK and a density of 1.21 g/cm3. This research also introduced a new way of fabricating lightweight heat sink for thermal management by a combination of 3D printing technology with carbon nanotube sheet. Our heat sink offered effective thermal performance and extremely lightweight. Results indicate that the techniques are effective ways to transfer the properties of CNT sheets into lightweight thermal devices for thermal management applications. Furthermore, this work demonstrated feasibility and preliminary results of a fully printed wireless sensor that can potentially operate, monitor and transfer high quality of signal such as a change in relative permittivity. The sensors can effectively detect the change in permittivity of the environment Printed wireless sensor could open cost-effective and efficient way to monitor the large composite structure or manufacturing process.
Show less
Date Issued: 2019
Identifier: 2019_Summer_Nguyen_fsu_0071E_15140
Format: Thesis

Title: Investigation of Single Crystal Perovskite for Mechanoluminescence-Based Sensor Application.
Creator: Braga Carani, Lucas, Okoli, Okenwa O. I., Dickens, Tarik, Yu, Zhibin, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing...
Show moreBraga Carani, Lucas, Okoli, Okenwa O. I., Dickens, Tarik, Yu, Zhibin, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Organic-inorganic halide perovskites have received significant attention as a promising opportunity for low-cost, high-performance optoelectronic devices, such as solar cells, photodetectors, and light-emitting diodes due to their excellent optoelectronic properties and considerable low-cost production processes. There is a great interest to investigate further the possibility of integrating perovskites with other materials for the development of efficient optoelectronic devices. This thesis...
Show moreOrganic-inorganic halide perovskites have received significant attention as a promising opportunity for low-cost, high-performance optoelectronic devices, such as solar cells, photodetectors, and light-emitting diodes due to their excellent optoelectronic properties and considerable low-cost production processes. There is a great interest to investigate further the possibility of integrating perovskites with other materials for the development of efficient optoelectronic devices. This thesis explores the feasibility of integration of single crystals perovskite and mechanoluminescent materials for the fabrication of pressure sensors. The combination and integration of the unique characteristics of perovskite crystals and mechanoluminescent materials are scarce in the literature. The integration of a perovskite layer and a mechanoluminescent material, such as ZnS:Cu can be used to fabricate a highly sensitive and fast-response device. This thesis will focus on the fabrication of an integrated sensing device made with two main components, a mechanoluminescent material layer, acting as a light-emitting layer, and a single crystal perovskite layer, functioning as a light-harvesting layer. This research covers all the process of the device fabrication and testing experiments under tensile and compression forces. The tests conducted proved that the light emitted by the mechanoluminescent material can be collected by a single crystal perovskite as an integrated sensing device. It is the initial step for further research on the utilization of perovskite materials for sensing devices.
Show less
Date Issued: 2019
Identifier: 2019_Fall_BragaCarani_fsu_0071N_15489
Format: Thesis

Title: Investigation of the Osmotic Drying of Alumina-Gelatin Objects Utilizing an Aqueous Poly(Ethylene glycol) Liquid Desiccant.
Creator: Hammel, Emily Catherine, Okoli, Okenwa O. I., Hruda, Simone Peterson, Liang, Zhiyong, Zhang, Mei, Florida State University, College of Engineering, Department of Industrial and...
Show moreHammel, Emily Catherine, Okoli, Okenwa O. I., Hruda, Simone Peterson, Liang, Zhiyong, Zhang, Mei, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Advanced ceramics and ceramic composites have a variety of advantageous properties, such as high hardness, strength, and wear resistance. This makes them good candidates for materials in the aerospace, automotive and defense industries, among others. A major disadvantage of advanced ceramics and ceramic composites is their requirement for specialized processing which often makes manufacturing complex shaped ceramic objects challenging and costly. Additionally, these materials are susceptible...
Show moreAdvanced ceramics and ceramic composites have a variety of advantageous properties, such as high hardness, strength, and wear resistance. This makes them good candidates for materials in the aerospace, automotive and defense industries, among others. A major disadvantage of advanced ceramics and ceramic composites is their requirement for specialized processing which often makes manufacturing complex shaped ceramic objects challenging and costly. Additionally, these materials are susceptible to flaw incorporation during production. These flaws are initiation points for failure and thus lead to a drastic reduction in strength. Repeatable manufacturing methods and optimized processes are compulsory for cost saving and production of high quality parts. In recent years, new processing technologies, such as gelcasting, have been developed to accommodate the formation of complex shaped ceramics and also the manufacture of ceramic composites. The use of wet forming technologies, like slip casting or gelcasting, necessitates the careful drying of ceramic objects. Complex shaped objects are particularly difficult to properly dry without introducing internal stresses which may result in warping and cracking, thus rendering the object unusable. Additionally, traditional drying processes are often energy intensive and lengthy, neither of which are favorable in a production setting. To improve manufacturability, the processing-structure-property relationships developed during the drying process must be investigated further. This work addresses the need to define optimized process conditions for the drying of alumina objects gelcast using gelatin. The osmotic drying process was employed to remove solvent from the objects through the use of an aqueous liquid desiccant solution of poly(ethylene glycol) (PEG). The process settings for the solution’s osmotic pressure and molecular weight were investigated, in addition to the total immersion time. The mass transfer processes that occurred between the ceramic object and the liquid desiccant solution were quantified in several case studies. For one sample, 40 weight% of the initial water content was removed in 75 minutes demonstrating the potential drying efficiency of this method. Depending on the initial solution conditions, the PEG solute was found to diffuse into the ceramic object to varying degrees. The effect of the drying condition on the object’s density and hardness was also measured. Through the development of regression equations, the process settings were optimized based on the goals to maximize water loss, minimize solids gain, and maximize the object’s density. The optimum drying settings for the objects studied in this work were an osmotic pressure of 2.50 MPa, a molecular weight of at least 100,000 g/mol, and an immersion time of 60 minutes. When objects of similar geometry, composition, and solution-to-object volume ratio are immersed in this type of solution, they are expected to lose 28 weight% of the object’s initial water content, gain solids of 0.82 weight% of the object’s initial mass, and have a density of 3.54 g/cm3. Furthermore, the regression models were validated using an independent experimental study. A model based on mass balance was used to define the kinetics of the mass transfer, along with the equilibrium values. Lastly, a demonstration of the feasibility of combining gelcasting, osmotic drying, and sacrificial templating is presented. Overall, these results may be used as the basis for further investigation into the scale up of the osmotic drying of gelcast alumina with the eventual implementation of the process in an industrial setting.
Show less
Date Issued: 2018
Identifier: 2018_Su_Hammel_fsu_0071E_14711
Format: Thesis

Title: Enhancing Polymer Composites with Triboluminescent Materials.
Creator: Scheiner, Margaret Victoria, Okoli, Okenwa O. I., Sobanjo, John Olusegun, Ma, Biwu, Yu, Zhibin, Dickens, Tarik, Florida State University, FAMU-FSU College of Engineering,...
Show moreScheiner, Margaret Victoria, Okoli, Okenwa O. I., Sobanjo, John Olusegun, Ma, Biwu, Yu, Zhibin, Dickens, Tarik, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Fiber-reinforced polymer composites (FRPCs) have a variety of applications in diverse industries. However, predicting the failure of FRPCs is more difficult than predicting the failure of more traditional materials like steel. Furthermore, composites can suffer extreme internal damage, but show little if any external indication that damage has occurred. This study investigated the potential for integrated structural health monitoring and self-healing for polymer composites utilizing...
Show moreFiber-reinforced polymer composites (FRPCs) have a variety of applications in diverse industries. However, predicting the failure of FRPCs is more difficult than predicting the failure of more traditional materials like steel. Furthermore, composites can suffer extreme internal damage, but show little if any external indication that damage has occurred. This study investigated the potential for integrated structural health monitoring and self-healing for polymer composites utilizing triboluminescent (TL) materials. This study followed three phases. In Phase 1, the effects of enhancing resins with TL zinc sulfide manganese (ZnS:Mn) and europium dibenzoylmethide triethylamine (EuD4TEA) phosphors were investigated, including optimization of the EuD4TEA synthesis process and development of a model for tensile modulus based on TL inclusion and type of resin. EuD4TEA should be synthesized using at minimum 80 mmol/L europium nitrate and 260 mmol/L DBM, with at least 80 mmol/L TEA. ZnS:Mn was observed to increase elastic modulus of vinyl ester and light-curable polyurethane, by 103% and 60%, respectively. The larger EuD4TEA crystals decreased vinyl ester’s (VE’s) elastic modulus by 11%, at least partly due to particle size. EuD4TEA-enhanced light-curing polyurethane suffered a 95% decrease in elastic modulus, mostly due to incomplete cure. Inclusion of EuD4TEA in the VE resin resulted in the formation of voids, approximately the size of the EuD4TEA crystals. Protecting the EuD4TEA crystals from the heat of cure reduced the formation of bubbles, and improved TL emissions. Thermogravimetric analysis indicated the NHEt3 group was lost as EuD4TEA was heated above 100 °C. In Phase 2, a new measurement system was developed to evaluate luminescence and longevity of TL-enhanced resins. Optical fibers with a tip coating of TL-enhanced resin both provided a stage for the sample and directed the TL emissions into a light sensor. This tip-coated optical fiber method results in less variation in TL signal for ZnS:Mn-enhanced VE and sucrose-enhanced VE samples than impacts on loose ZnS:Mn and sucrose crystals. The intensity of TL emissions may be increased sevenfold by exposing the TL-enhanced sample to ultraviolet light immediately prior to TL testing. In Phase 3, the potential for TL-induced polymerization (and, by extension, TL-induced healing) was assessed. The results show polymers may be cured with visible light, even low-intensity photoluminescence, indicating feasibility of TL-induced healing.
Show less
Date Issued: 2018
Identifier: 2018_Sp_Scheiner_fsu_0071E_14378
Format: Thesis

Title: Auxetic and Hybrid Structure Designs and Advanced Manufacturing Study for Energy Absorption Improvements.
Creator: Ingrole, Aniket Arvind, Liang, Zhiyong, Jung, Sungmoon, Zeng, Changchun, Dickens, Tarik, Florida State University, College of Engineering, Department of Industrial and...
Show moreIngrole, Aniket Arvind, Liang, Zhiyong, Jung, Sungmoon, Zeng, Changchun, Dickens, Tarik, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: One of the major concerns for many athletes in todays' sports is mild Traumatic Brain Injury (mTBI), which is commonly known as concussion. Researchers and manufacturers of sport helmets are constantly trying to develop new designs and technologies to better prevent mTBI. The objective of this research is to study the effective designs for sport helmets that can potentially absorb and dispel both linear and rotational forces acting on the head during impact. Inspiration by the different types...
Show moreOne of the major concerns for many athletes in todays' sports is mild Traumatic Brain Injury (mTBI), which is commonly known as concussion. Researchers and manufacturers of sport helmets are constantly trying to develop new designs and technologies to better prevent mTBI. The objective of this research is to study the effective designs for sport helmets that can potentially absorb and dispel both linear and rotational forces acting on the head during impact. Inspiration by the different types of working mechanisms and structures existing in nature that can absorb energy from different types of impacts, new designs were explored. Honeycomb structures have been used extensively in lightweight sandwich structure and impact energy absorption applications. Recently, Auxetic structures are attractive for various engineering applications because of their unique mechanical properties, volume change control and excellent impact energy absorption performance. In this study, novel designs and performance improvement of new auxetic-strut structures were presented. A comparative study of in-plane and out-of-plane uniaxial compression loading behavior of regular honeycomb, re-entrant auxetic honeycomb, locally reinforced auxetic-strut structure and a hybrid structure of combining regular honeycomb and auxetic-strut structure was conducted. Finite element modelling was carried out to reveal their structure-property relationships. The deformation and failure modes of the different designs were studied and their performance was also discussed. The new auxetic-strut structure showed better mechanical properties than the honeycomb and auxetic structures with a small density increase. For in-plane performance, the compressive strength of the auxetic-strut design is ~300% more than that of honeycomb structure and ~65% more than that of auxetic structure. With lower values of the Poisson’s ratio, the new design can absorb more energy when compared to the other structures. The out-of-plane properties of auxetic-strut design showed an increase of ~68% in the compressive strength, ~63% in Young’s modulus and ~32% in the total energy absorbed when compared with the honeycomb structure. The hybrid structures also showed excellent out-of-plane properties. With better in-plane and out-of-plane properties, auxetic-strut design can be used in various energy absorption applications. Hybrid designs allow us to tailor properties of the structures with their specific in-plane and out-of-plane deformation and failure modes A comparative study of dynamic crushing behavior of the structures was also carried out. Finite element modelling was conducted to compare the dynamic crushing behavior of these structures at different impact velocities. Deformation mechanisms of these structures were studied, that provided the new insights on how to control the deformation of the structure and tailor the properties. For in-plane impact tests the energy absorbed by auxetic- strut and hybrid structures was half when compared with honeycomb and re-entrant auxetic structures at lower strain levels. But at higher strain levels, the new structures performed twice as that of the later. In contrary for out-of-plane crushing, the energy absorbed by the auxetic-strut and hybrid structures was higher than the honeycomb and re-entrant auxetic structures at lower strain levels and vice-versa. Advanced manufacturing or 3D printing method were employed to produce samples of the new designs. The results of the sample tests are in good agreement with the modeling predictions. These results are valuable to provide new fundamental understanding of structure-property relationships for new auxetic-strut and their hybrid honeycomb structures for potential aerospace and sporting product applications, especially in football helmets.
Show less
Date Issued: 2018
Identifier: 2018_Sp_Ingrole_fsu_0071E_14338
Format: Thesis

Title: Supply Prepositioning for Disaster Management.
Creator: Baloglu, Aysegul, Vanli, Omer Arda, Wang, Hui, Park, Chiwoo, Ozguven, Eren Erman, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and...
Show moreBaloglu, Aysegul, Vanli, Omer Arda, Wang, Hui, Park, Chiwoo, Ozguven, Eren Erman, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: This thesis studies two-stage stochastic optimization methods for supply prepositioning for hurricane relief logistics. The first stage determines where to preposition supplies and how much to preposition at a location. The second stage decides the amount of supplies distributed from supply centers to demand centers. The methods proposed are (I) a method to minimize the expected total cost (II) a method to minimize the variance of the total cost that accounts for the uncertainties of...
Show moreThis thesis studies two-stage stochastic optimization methods for supply prepositioning for hurricane relief logistics. The first stage determines where to preposition supplies and how much to preposition at a location. The second stage decides the amount of supplies distributed from supply centers to demand centers. The methods proposed are (I) a method to minimize the expected total cost (II) a method to minimize the variance of the total cost that accounts for the uncertainties of parameters of the expected cost model. For method II, a Bayesian model and a robust stochastic programming solution approach are proposed. In this approach the cost function parameters are assumed to be uncertain random variables. We propose a Mixed Integer Programming model, which can be solved efficiently using linear and nonlinear programming solvers. The resultslinear and nonlinear integer programming problems are obtained solved using CPLEX and FILMINT solvers, respectively. A computational case study comprised of real-world hurricane scenarios is conducted to illustrate how the proposed methods work on a practical problem. A buffer zone is specified in order to be sent of the commodities to a certain distance. Estimation of hurricane landfall probabilities and the effect of cost uncertainty on prepositioning decisions is considered.We propose a Mixed Integer Programming model, which can be solved efficiently using a linear and nonlinear programming solver. The results are obtained using CPLEX and FILMINT.
Show less
Date Issued: 2018
Identifier: 2018_Sp_Baloglu_fsu_0071N_14559
Format: Thesis

Title: Scalable Manufacturing of Perovskite Polymer Composites Towards Advanced Optoelectronics.
Creator: Shan, Xin, Yu, Zhibin, Zheng, Jianping, Liang, Zhiyong, Vanli, Omer Arda, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing...
Show moreShan, Xin, Yu, Zhibin, Zheng, Jianping, Liang, Zhiyong, Vanli, Omer Arda, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Halide perovskites bring an unprecedented opportunity for low-cost high performance optoelectronic devices due to their extraordinary optical and electrical properties along with their solution processible nature. The record power conversion efficiency (PCE) of perovskite solar cells (23.3%) has surpassed polycrystalline silicon, copper indium gallium selenide (CIGS), and cadmium telluride (CdTe). In addition, the record external quantum efficiency (EQE) of perovskite light-emitting diodes ...
Show moreHalide perovskites bring an unprecedented opportunity for low-cost high performance optoelectronic devices due to their extraordinary optical and electrical properties along with their solution processible nature. The record power conversion efficiency (PCE) of perovskite solar cells (23.3%) has surpassed polycrystalline silicon, copper indium gallium selenide (CIGS), and cadmium telluride (CdTe). In addition, the record external quantum efficiency (EQE) of perovskite light-emitting diodes (20.3%) is on par with the organic light-emitting diodes (OLEDs) and quantum dot light-emitting diodes (QLEDs). Benefiting from the superb properties of perovskites, there is increasing interests in fabricating perovskite optoelectronics in a large scale as well as with low elastic modulus (high flexibility and stretchability). Although the efficiencies of perovskite optoelectronics increase dramatically in the past few years, there are still concerns that cause short lifespan in perovskite optoelectronics, such as ion migration induced intrinsic perovskite instability, oxygen, moisture, non-radiative recombination at the constituent layer interfaces. This dissertation explores the possibility of scalable manufacturing of optoelectronics with low elastic modulus using perovskite polymer composites. Besides, this dissertation also studies the ion migration induced in-situ junction formation in halide perovskite polymer composite films and perovskite single crystals. Device failure mechanism caused by ion migration is also investigated in this dissertation. Perovskite thin film processing is essential for perovskite optoelectronics scalable manufacturing. In this dissertation, firstly, a uniform and pin-hole free thin film was processed using perovskite polymer composites. Perovskite LEDs were fabricated using the composite emitters. It has been discovered that an in situ homogeneous p-i-n junction can be developed in the composite emitter when an external bias is applied. The junction formation enables very efficient charge carrier transportation in perovskite LEDs without using additional electron transport layers (ETLs) and hole transport layers (HTLs). While a typical LED usually adopts a multi-layer structure, including both ETLs and HTLs. The unique simplified perovskite LED structure without using ETLs and HTLs is called "single-layer" structure. Moreover, scalable manufacturing of fully printed perovskite LEDs and intrinsically stretchable LEDs with robust mechanical performance is demonstrated benefiting from the "single-layer" structure in this dissertation. A stable junction formation is the basis of a stable perovskite LED. In this dissertation, the in-situ p-i-n homojunction in the perovskite polymer composites and perovskite single crystals are studied. AC impedance spectroscopy is used to study the junction formation and propagation of the perovskite polymer composites under an external electric field. Discharge current-voltage (I-V) characteristics and temperature dependence study are also conducted to support the ion migration induced junction formation and relaxation. It is a potential pathway to obtain highly stable perovskite LEDs by immobilizing the ions and stabilizing the junction.
Show less
Date Issued: 2018
Identifier: 2018_Fall_Shan_fsu_0071E_14859
Format: Thesis

Title: Architected Multiscale Polymer Foams.
Creator: Ahmed, Mohammad Faisal, Zeng, Changchun, Shanbhag, Sachin, Liang, Zhiyong, Yu, Zhibin, Florida State University, College of Engineering, Department of Industrial and...
Show moreAhmed, Mohammad Faisal, Zeng, Changchun, Shanbhag, Sachin, Liang, Zhiyong, Yu, Zhibin, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Polymeric foam materials continue to gather commercial and research interests due to their unique physical characteristics and emerging applications in a wide variety of industries. This research work viewed the polymer foam industry from three different perspectives, namely materials, processes and applications. Accordingly, technical challenges were carefully selected to make contributions towards each segment by expanding materials choice, proposing architected foam fabrication process and...
Show morePolymeric foam materials continue to gather commercial and research interests due to their unique physical characteristics and emerging applications in a wide variety of industries. This research work viewed the polymer foam industry from three different perspectives, namely materials, processes and applications. Accordingly, technical challenges were carefully selected to make contributions towards each segment by expanding materials choice, proposing architected foam fabrication process and exploring multifunctional applications of foam sensors. Thermoplastic elastomers are thermally processable yet rubberlike materials which experience shrinkage when operated between the glass transition temperatures of soft rubbery phase and hard phase. This brings a challenge in making microcellular foams using batch foaming process where the materials are not fully melted to generate cellular structure. The issue was addressed in this research by incorporating a second phase (i.e. a polymer blend system) to perform as a shape fixing unit. Thus, a series of thermoplastic polyurethane (TPU) elastomeric foams were prepared by blending polylactic acid (PLA) as the shape fixing unit. The morphological, thermal and rheological behavior of the blend system was studied prior to foaming. The blends that contained PLA as the minor phase resulted in foams with high expansion ratio. These blend foams were compared to TPU foams in terms of shape fixity ratio. The results were fitted with Kohlrausch-Williams-Watts (KWW) function to estimate foam relaxation times. Foam relaxation time and shape fixity ratio increased with increasing PLA content. The glass transition temperature of PLA performed as the anchor point to stabilize the foam structure. Architected polymeric materials when designed for specific application could satisfy design requirements with desired unit cell design for having controllable pore size, pore density and pore connectivity. With development of additive manufacturing, fabrication of macro, micro and even nano porous structures have become a possibility. In this research, a new route to fabricating architected multiscale polymer foam is proposed and consequently studied in detail with a view to realizing its potential as a near net-shape process. The fabrication process utilized the synergy of additive manufacturing and batch foaming process to induce macro and microporosity (i.e. structural hierarchy). The results suggested that the process can generate foams with more than 95% expansion uniformity with significantly reduced saturation time. The process is also capable of handling a variety of thermoplastics which also includes polymer blends. Traditional applications of polymeric materials include insulation, energy absorption, floatation, packaging and so on. Though a relatively new concept, multifunctional foams have attracted the research community to develop and explore applications of materials that utilize foams as the skeleton. Such materials demonstrate sensing capability for having piezoresistive characteristics induced by conductive nanomaterials. Piezoresistive auxetic foams sensors coated with silver nanowire were prepared in this research to demonstrate their application as pressure sensors, 3D strain sensors, smart filtration and human motion interface. The auxetic foam sensors reported herein demonstrated improved piezoresistive properties compared to conventional counterpart and showed repeatable and reliable sensing performance for a variety of deformation modes.
Show less
Date Issued: 2018
Identifier: 2018_Su_Ahmed_fsu_0071E_14717
Format: Thesis

Title: Scalable Manufacturing of Lightweight Morphing Structures Using Carbon Nanotube Buckypaper.
Creator: DeGraff, Joshua, Liang, Zhiyong, Hruda, Simone Peterson, Cottinet, Pierre-Jean, Zeng, Changchun, Vanli, Omer Arda, Florida State University, College of Engineering, Department...
Show moreDeGraff, Joshua, Liang, Zhiyong, Hruda, Simone Peterson, Cottinet, Pierre-Jean, Zeng, Changchun, Vanli, Omer Arda, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Intelligent morphing structures will revolutionize micro-robotics, wearable technology, and tiny electro-mechanical systems. The ideal morphing structure is thin and flexible with the ability to deform and sense its surroundings. Biological organisms provide the inspiration for this kind of technology. By developing a low-profile film that changes shape and detects ambient conditions, it will provide leeway to mimicking the way organisms move throughout various mediums and terrains, while...
Show moreIntelligent morphing structures will revolutionize micro-robotics, wearable technology, and tiny electro-mechanical systems. The ideal morphing structure is thin and flexible with the ability to deform and sense its surroundings. Biological organisms provide the inspiration for this kind of technology. By developing a low-profile film that changes shape and detects ambient conditions, it will provide leeway to mimicking the way organisms move throughout various mediums and terrains, while deliberating their next actions according to the current environment and the actions that they have previously attempted. This dissertation will introduce carbon nanotube buckypaper as a key material in facilitating intelligent morphing schemes. In this research, a scalable manufacturing process for producing buckypaper composite actuators is introduced. The process can produce large batches of actuators at a time; this is critical for designing complex morphing structures in the future. The research also includes the electro-chemical modelling of the buckypaper composite actuator. Many researchers have introduced their own designs for actuators; however, most actuators lack the sensing component needed to be considered in morphing structures. This research will introduce a scalable method for buckypaper strain sensors as well. The sensors can detect micro-strains with higher sensitivity than commercial strain gauges. They can also detect finger movements and micro-strains in carbon composite materials. The overall objective is to synchronize the two devices so that a closed-loop system can provide corrections to the actuators movements. This research is essential to progressing low-profile morphing structures.
Show less
Date Issued: 2018
Identifier: 2018_Su_Degraff_fsu_0071E_14511
Format: Thesis

Title: Preparation and Application of Piezoelectric Foams Based on Cyclic Olefin Copolymers.
Creator: Wang, Hui, Zeng, Changchun, Oates, William, Liang, Zhiyong, Vanli, Omer Arda, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and...
Show moreWang, Hui, Zeng, Changchun, Oates, William, Liang, Zhiyong, Vanli, Omer Arda, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: The goal of this research is to fabricate, characterize and apply the designed polymer based porous piezoelectric material into practical use. In line with the goal, the research objectives are: Select proper materials that have potential to serve as non-toxic, high sensitivity, low cost, light weight, flexible and heat durable piezoelectric materials. Setup fabrication process of piezoelectric foam and enable the piezoelectric material to have piezoelectricity. Characterize the sensitivity,...
Show moreThe goal of this research is to fabricate, characterize and apply the designed polymer based porous piezoelectric material into practical use. In line with the goal, the research objectives are: Select proper materials that have potential to serve as non-toxic, high sensitivity, low cost, light weight, flexible and heat durable piezoelectric materials. Setup fabrication process of piezoelectric foam and enable the piezoelectric material to have piezoelectricity. Characterize the sensitivity, heat durability, charge storage process, capability and actuation behavior of the material. Identify the most significant parameters that affect the performance of the material and optimize the structure design of the material. Apply the piezoelectric material as piezoelectric pressure sensor, impact sensor and other applications.
Show less
Date Issued: 2018
Identifier: 2018_Su_Wang_fsu_0071E_14535
Format: Thesis

Title: Extending and Simplifying Existing Piecewise-Linear Homotopy Methods for Solving Nonlinear Systems of Equations.
Creator: Wheaton, Ira Monroe, Awoniyi, Samuel A. (Samuel Ayodele), Foo, Simon Y., Park, Chiwoo, Vanli, Omer Arda, Florida State University, FAMU-FSU College of Engineering, Department of...
Show moreWheaton, Ira Monroe, Awoniyi, Samuel A. (Samuel Ayodele), Foo, Simon Y., Park, Chiwoo, Vanli, Omer Arda, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: This dissertation research extends and simplfiies existing piecewise-linear homotopy (PL) methods to solve G(x) = 0, with G : ℝⁿ → ℝ[superscript m]. Existing PL methods are designed to solve F(x) = 0, with F : ℝⁿ → ℝⁿ and some related point-to-set mappings. PL methods are a component of what is also known as numerical continuation methods, and they are known for being globally convergent methods. First, we present a new PL method for computing zeros of functions of the form ƒ : ℝⁿ → ℝ by...
Show moreThis dissertation research extends and simplfiies existing piecewise-linear homotopy (PL) methods to solve G(x) = 0, with G : ℝⁿ → ℝ[superscript m]. Existing PL methods are designed to solve F(x) = 0, with F : ℝⁿ → ℝⁿ and some related point-to-set mappings. PL methods are a component of what is also known as numerical continuation methods, and they are known for being globally convergent methods. First, we present a new PL method for computing zeros of functions of the form ƒ : ℝⁿ → ℝ by mimicking classical PL methods for computing zeros of functions of the form ƒ : ℝ → ℝ. Our PL method avoids traversing subdivisions of ℝⁿ x [0, 1] and instead uses an object that we refer to as triangulation-graph, which is essentially a triangulation of ℝ x [0, 1] with hypercubes of ℝⁿ as its vertices. The hypercubes are generated randomly, and a sojourn time of an associated discrete-time Markov chain is used to show that not too many cubes are generated. Thereafter, our PL method is applied to solving G(x) = 0 for G : ℝⁿ → ℝ[superscript m] under inequality constraints. The resultant method for solving G(x) = 0 translates into a new type of iterative method for solving systems of linear equations. Some computational illustrations are reported. A possible application to optimization problems is also indicated as a direction for further work.
Show less
Date Issued: 2017
Identifier: FSU_2017SP_Wheaton_fsu_0071E_13419
Format: Thesis

Title: Laser Heat Treatment Processing for Pan Based Carbon Fiber Structure Modification.
Creator: Daniels, Esther Osemudiamen, Zhang, Mei, Zeng, Changchun (Chad), Dickens, Tarik J., Florida State University, College of Engineering, Department of Industrial and Manufacturing...
Show moreDaniels, Esther Osemudiamen, Zhang, Mei, Zeng, Changchun (Chad), Dickens, Tarik J., Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Carbon fiber is one of the most successful fibers in over 30 years as a result of its high specific strength and modulus, good coefficient of thermal expansion, and its excellent fatigue, and corrosion resistance. From its early use in the military and aerospace applications, carbon fiber composites have become a good light weight replacement material in place of heavier materials like metals (such as steel and aluminum) without compromise on the required mechanical properties....
Show moreCarbon fiber is one of the most successful fibers in over 30 years as a result of its high specific strength and modulus, good coefficient of thermal expansion, and its excellent fatigue, and corrosion resistance. From its early use in the military and aerospace applications, carbon fiber composites have become a good light weight replacement material in place of heavier materials like metals (such as steel and aluminum) without compromise on the required mechanical properties. Polyacrylonitrile (PAN) -based carbon fiber accounts for over 90% of the global demand today as a result of its superior tensile strength and light weight properties. As a good structural reinforcement material, the demand for this fiber continues to grow in high-end applications but is largely limited in industrial and commercial applications by its high cost; accrued from the procurement of the PAN precursor and its manufacturing costs (which involves pyrolysis at temperatures up to 3000° C supplied by a furnace based heating system). This current manufacturing system is characterized by energy losses and slow processing rates which make it inefficient. Also, the large facility requirement and high production costs contribute to the high cost of the fiber. Hence, more cost effective processing systems are desired in meeting the growing demand of this fiber. This research demonstrates the use of the laser as an alternative heat treatment source based on its fast and high energy generation capabilities. In this study, the CO2 continuous pulsed wave laser was employed due to its higher energy generation capabilities. As the laser beam radiated on the surface of the fiber, the energy produced from the laser beam caused the fiber's atoms to vibrate and restructure themselves along the direction of the laser scan. By varying the laser scan settings, changes in the structure of the laser treated low-grade carbon fibers were investigated with the aim of increasing the fibrilla orientation during the graphitization process. The laser treated fibers tested exhibited internal structural changes indicative of plausible structural alignment in the fiber. Lasers provide highly concentrated and localized energy at a high speed of operation. In understanding the process conditions, preliminary understudy of the interrelationship between the lasing parameters and structure of the treated fibers formed in this research were reported. This novel study provided more insight in the microstructure enhancement of carbon fiber possible with use of the laser during the carbon fiber manufacturing process.
Show less
Date Issued: 2017
Identifier: FSU_2017SP_Daniels_fsu_0071N_13645
Format: Thesis

Title: Regressing over Linear-Circular Data Using a Mixture of Linear-Linear Regression Models.
Creator: Esmaieeli-Sikaroudi, Ali, Park, Chiwoo, Vanli, Omer Arda, Shanbhag, Sachin, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Abstract/Description: Regression over circular response data requires special methods due to the periodic nature of this data type. In previous works, researchers tried to use the concept of projecting real-line distributions on unit circles or using transformation methods to transform circular response to real-line and wise versa; however, their methods only work for simple data and in some cases they are really complicated and slow. In this research circular responses are treated as the output of the modulo...
Show moreRegression over circular response data requires special methods due to the periodic nature of this data type. In previous works, researchers tried to use the concept of projecting real-line distributions on unit circles or using transformation methods to transform circular response to real-line and wise versa; however, their methods only work for simple data and in some cases they are really complicated and slow. In this research circular responses are treated as the output of the modulo operation on unobserved linear responses. A mixture of multiple linear-linear regression models is used to implement this idea. We used Gaussian Mixture method to model the data and Gibbs sampling to tune the parameters. The idea itself would be a new way to look at the linear-circular regression problem and can be used as the foundation of the other methods to be developed in future.
Show less
Date Issued: 2017
Identifier: FSU_2017SP_EsmaieeliSikaroudi_fsu_0071N_13833
Format: Thesis

Title: Ensemble Pruning Algorithms in Machine Learning.
Creator: Agbabiaka, Adeseye, Park, Chiwoo, Shanbhag, Sachin, Awoniyi, Samuel A. (Samuel Ayodele), Vanli, Omer Arda, Florida State University, College of Engineering, Department of...
Show moreAgbabiaka, Adeseye, Park, Chiwoo, Shanbhag, Sachin, Awoniyi, Samuel A. (Samuel Ayodele), Vanli, Omer Arda, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Ensemble learning algorithms are among the most widely used and indispensable tools in machine learning, data science and predictive analytics. Their widespread use can be attributed to the success of ensemble learning algorithms in various applications. As a result of their usefulness in statistical learning to improve generalization performance, several ensemble learning algorithms have been developed over the years. However, the use of ensemble learning models comes with some additional...
Show moreEnsemble learning algorithms are among the most widely used and indispensable tools in machine learning, data science and predictive analytics. Their widespread use can be attributed to the success of ensemble learning algorithms in various applications. As a result of their usefulness in statistical learning to improve generalization performance, several ensemble learning algorithms have been developed over the years. However, the use of ensemble learning models comes with some additional computational and storage cost, since ensembles are a collection of many individual learning models that jointly work together to solve a problem. In other to alleviate problems associated with using ensemble learning algorithms, the sub-field of ensemble pruning was born. It involves the optimal selection of a subset of ensemble learning models from a collection of the full ensemble without compromising the predictive performance of the original full ensemble. The objective of this dissertation is to improve upon existing ensemble pruning algorithms and to develop new and more efficient competitive methods. Given an initial set of predictive models, an ensemble pruning algorithm tries to select a subset of the ensemble set such that the selected subset does not compromise the performance of the full ensemble, therefore the ensemble pruning problem can be conceived as a subset selection problem. A modified form of an existing pruning algorithm known as SDP based pruning algorithm is proposed. The modified algorithm is based on the use of better evaluation measure to guide the greedy search part of the original algorithm. The weighted vote accuracy is used to improve the performance of the original algorithm. Drawing inspiration from the original as well as the modified algorithm the author proposes two versions of an algorithm, Partial Greedy Randomized Ensemble Pruning (PAGREP) algorithm. Each version of this algorithm has two distinct parts to it, the first being the solution of a rigorously formulated optimization problem and the second part is a heuristic randomized greedy search procedure. The original algorithm improved upon while being very competitive with the state-of-the-art algorithms and achieving the goals of ensemble pruning however, turns out not to scale properly to large sized ensemble in terms of computational efficiency. The two versions of the PAGREP algorithm being proposed overcomes this shortcoming and are able to efficiently prune larger sized ensembles while at the same time maintaining the predictive performance of the original SDP based algorithm and even slightly outperforming it. Based on the successes of the algorithms the author believes that further refinement and development of algorithms of this nature consisting of a first part which involve the solution of a rigorously formulated optimization problem and a second part of a greedy search procedure could be a formidable alternative to current state-of-the-art algorithms and even outperform them when fully developed. In the last chapter we propose two other algorithms for ensemble pruning, the first one is based on the use of an alternative solution method for solving the SDP problem which arises in the SDP based ensemble pruning algorithm. The alternative solution method of the SDP, known as the SDCut efficiently solves the dual problem of the SDP and thereafter obtains the primal solution of the original SDP problem from the dual solution. The SDCut method being a recently developed procedure for solving SDPs outperforms all other SDP solution method and it is used for solving the SDP problem in the original SDP based pruning algorithm. We also apply the particle swarm optimization (PSO) algorithm to the ensemble pruning problem using the weighted vote error as the fitness function to be minimized and shows that it is both competitive in terms of predictive accuracy and efficient for producing sub-ensembles. Computational experiments of all the proposed algorithms on benchmark datasets from the UCI repository shows the improved performance of the algorithms.
Show less
Date Issued: 2017
Identifier: FSU_2017SP_Agbabiaka_fsu_0071E_13572
Format: Thesis

Title: Iterative Multi-Task Learning on Spatial Time Series Data with Applications to Improvement of Performance Prediction and Monitoring for Solar Panels.
Creator: Shireen, Tahasin, Wang, Hui, Zhang, Mei, Shrivastava, Abhishek Kumar, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Abstract/Description: Health condition monitoring and failure detection play a crucial role in estimating the performance of solar panels such as degradation trend over time and occurrence of failures. Monitoring and detecting significant degradation can help solar panel owners establish as-needed maintenance strategies on a timely manner. But in some occasions, degradation trend estimation becomes challenging due to limited availability of training data such as many missing observations in time series over a...
Show moreHealth condition monitoring and failure detection play a crucial role in estimating the performance of solar panels such as degradation trend over time and occurrence of failures. Monitoring and detecting significant degradation can help solar panel owners establish as-needed maintenance strategies on a timely manner. But in some occasions, degradation trend estimation becomes challenging due to limited availability of training data such as many missing observations in time series over a large time span and a lack of history of failure records that are sufficient to establish statistical models. To fill the gap, this thesis proposes a new approach of iterative multi-task learning of Gaussian process in time series data (MTL-GP-TS) by sharing information among similar-but-not-identical datasets from multiple solar panel locations. The proposed MTL-GP-TS model learns unobserved or missing values in a particular time series dataset to forecast the future trend with autoregressive integrated moving average (ARIMA) model, resulting in substantial improvement of forecast over conventional time series modeling approaches. Moreover, the estimated degradation trend with proposed MTL-GP-TS method has the potential to improve the monitoring of significant performance degradation compared with the conventional time series model. This thesis also studies the effect of temporal dependent weather factors on the solar panel performance by integrating a covariate with the MTL-GP-TS algorithm. A case study has demonstrated that inclusion of weather factors into the monitoring of degradation with PV-Weather data integration model can significantly improve the solar panel performance prediction.
Show less
Date Issued: 2016
Identifier: FSU_2016SP_Shireen_fsu_0071N_13167
Format: Thesis

Title: Scalable Fabrications of Nanomaterial Based Piezoresistivity Sensors with Enhanced Performance.
Creator: Tran, Hoang Phong, Yu, Zhibin, Liu, Tao (Ted), Zheng, Jianping P., Zeng, Changchun (Chad), Zhang, Mei, Florida State University, College of Engineering, Department of Industrial...
Show moreTran, Hoang Phong, Yu, Zhibin, Liu, Tao (Ted), Zheng, Jianping P., Zeng, Changchun (Chad), Zhang, Mei, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Nanomaterials are small structures that have at least one dimension less than ~100 nanometers. Depending on the number of dimensions that are not confined to the nanoscale range, nanomaterials can be classified into 0D, 1D and 2D types. Due to their small sizes, nanoparticles possess exceptional physical and chemical properties which opens a unique possibility for the next generation of strain sensors that are cheap, multifunctional, high sensitivity and reliability. Over the years, thanks to...
Show moreNanomaterials are small structures that have at least one dimension less than ~100 nanometers. Depending on the number of dimensions that are not confined to the nanoscale range, nanomaterials can be classified into 0D, 1D and 2D types. Due to their small sizes, nanoparticles possess exceptional physical and chemical properties which opens a unique possibility for the next generation of strain sensors that are cheap, multifunctional, high sensitivity and reliability. Over the years, thanks to the development of new nanomaterials and the printing technologies, a number of printing techniques have been developed to fabricate a wide range of electronic devices on diverse substrates. Nanomaterials based thin film devices can be readily patterned and fabricated in a variety of ways, including printing, spraying and laser direct writing. In this work, we review the piezoresistivity of nanomaterials of different categories and study various printing approaches to utilize their excellent properties in the fabrication of scalable and printable thin film strain gauges. CNT-AgNP composite thin films were fabricated using a solution based screen printing process. By controlling the concentration ratio of CNTs to AgNPs in the nanocomposites and the supporting substrates, we were able to engineer the crack formation to achieve stable and high sensitivity sensors. The crack formation in the composite films lead to piezoresistive sensors with high GFs up to 221.2. Also, with a simple, low cost, and easy to scale up fabrication process they may find use as an alternative to traditional strain sensors. By using computer controlled spray coating system, we can achieve uniform and high quality CNTs thin films for the fabrication of strain sensors and transparent / flexible electrodes. A simple diazonium salt treatment of the pristine SWCNT thin film has been identified to be efficient in greatly enhancing the piezoresistive sensitivity of SWCNT thin film based piezoresistive sensors. The coupled mechanical stretching and Raman band shift characterization provides strong evidence to support this point of view. The same approach should be applicable to other types of carbon based strain sensors for improving their sensitivity. The direct laser writing (DLW) method has been used for producing flexible piezoresistive sensor and sensor arrays on polyimide film substrates. The effect of CO2 laser irradiation conditions on the morphology, chemical composition and piezoresistivity of the formed graphitic line features were systematically studied to establish the related processing-structure-property relationship. The DLW generated sensors have been demonstrated for their use as strain gauges for structural health monitoring of polymeric composites, and as flexible and wearable sensors of gesture recognition for human-machine interactions. The versatility of the DLW technique demonstrated in this work can be highly valuable in different industrial sectors for developing customized flexible electronics.
Show less
Date Issued: 2016
Identifier: FSU_FA2016_Tran_fsu_0071E_13515
Format: Thesis

Title: Structural Health Monitoring with Lamb-Wave Sensors: Problems in Damage Monitoring, Prognostics and Multisensory Decision Fusion.
Creator: Mishra, Spandan, Vanli, Omer Arda, Okoli, Okenwa, Jung, Sungmoon, Park, Chiwoo, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and...
Show moreMishra, Spandan, Vanli, Omer Arda, Okoli, Okenwa, Jung, Sungmoon, Park, Chiwoo, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Carbon ﬁber reinforced composites (CFRC) have several desirable traits that can be exploited in the design of advanced structures and systems. The applications requiring high strength- to-weight ratio and high stiﬀness-to-weight ratio such as, fuselage of airplanes, wind turbine blades, water-boats etc. have found profound use of CFRC. Furthermore, low density, good vibration damping ability, easy manufacturability, carbon ﬁber’s electrical conductivity, as well as high thermal conductivity...
Show moreCarbon ﬁber reinforced composites (CFRC) have several desirable traits that can be exploited in the design of advanced structures and systems. The applications requiring high strength- to-weight ratio and high stiﬀness-to-weight ratio such as, fuselage of airplanes, wind turbine blades, water-boats etc. have found profound use of CFRC. Furthermore, low density, good vibration damping ability, easy manufacturability, carbon ﬁber’s electrical conductivity, as well as high thermal conductivity and smooth surface ﬁnish provide additional beneﬁts to the users. Various applications of CFRC can be relevant for aerospace, military, wind-turbines, robotics, sports equipment etc. However, among many advantages of CFRC there are a few disadvantages; CFRC undergo completely diﬀerent failure patterns compared to metals. Once the yield strength is exceeded, CFRC will fail suddenly and catastrophically. The inherent anisotropic nature of CFRC makes it very diﬃcult for traditional condition monitoring methods to assess the condition of the structure. The complex failure patterns, including delamination, micro-cracks, and matrix-cracks require specialized sensing and monitoring schemes for composite structure. This Ph.D. research is focuses on developing an integrated structural health monitoring methodology for damage monitoring, remaining useful life estimation (RUL), and decision fusion using Lamb-wave data. The main objective of this research is to develop an integrated damage detection method that utilizes Lamb-wave sensor data to infer the state of the damage condition and make an accurate prognosis of the structure. Slow fatigue loading results in very unique failure patterns in the CFRC structures, fatigue damage ﬁrst manifests itself as ﬁber-breakage and then slowly progresses to matrix-cracks and that ultimately leads to delamination damage. This type of failure process is very diﬃcult to monitor using the traditionally used damage monitoring methods such as X-ray evaluation, ultrasonic evaluation, infrared evaluation etc. For this research, we have used principal component (PC) based multivariate cumulative sum (MCUSUM) to monitor the structure. MCUSUM chart is very useful when monitoring structures undergoing slow and gradual change. For remaining-useful-life (RUL) estimation, we have proposed to use the Wiener process model coupled with principal component regression (PCR). For damage detection/classiﬁcation we studied discriminant analysis, in-spite of the popular use in image analysis and in the gene data classiﬁcation problem, has not been widely used for damage classiﬁcation. In this research, we showed that discriminant analysis is a useful detecting known damage modes, while dealing with the high dimensionality of Lamb-wave data. We modiﬁed the standard Gaussian discriminant analysis by introducing regularization parameters to directly process raw Lamb-wave data without requiring an intermediate feature extraction step.
Show less
Date Issued: 2016
Identifier: FSU_2016SU_Mishra_fsu_0071E_13346
Format: Thesis

Title: Aging Driver Focused Traffic Crash Frequency and Severity Analyses.
Creator: Omidvar, Aschkan, Vanli, Omer Arda, Ozguven, Eren Erman, Shrivastava, Abhishek Kumar, Park, Chiwoo, Florida State University, FAMU-FSU College of Engineering, Department of...
Show moreOmidvar, Aschkan, Vanli, Omer Arda, Ozguven, Eren Erman, Shrivastava, Abhishek Kumar, Park, Chiwoo, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: The aim of this thesis is to investigate the effect of environmental and traffic-related factors on the frequency and severity of highway crashes with a focus on different age groups including the aging populations. Existing studies in the traffic safety have not specifically focused on aging driver-involved crashes. Aging drivers are more vulnerable to the roadway crashes than other adult age groups due to their cognitive, physical and health limitations. This problem becomes more...
Show moreThe aim of this thesis is to investigate the effect of environmental and traffic-related factors on the frequency and severity of highway crashes with a focus on different age groups including the aging populations. Existing studies in the traffic safety have not specifically focused on aging driver-involved crashes. Aging drivers are more vulnerable to the roadway crashes than other adult age groups due to their cognitive, physical and health limitations. This problem becomes more challenging due to the drastic variation in the traffic patterns that especially happen on the major highways. In this thesis, several data sets from different sources, such as the National Oceanic and Atmospheric Administration (NOAA) and Florida Automated Weather Network (FAWN), the Florida Department of Transportation (FDOT) and the United States Naval Observatory (USNO), are collected, refined and combined. With the aid of statistical correlation analysis and logistic regression, a top down analysis is performed in order to analyze the occurrence of crashes via a case study application on the I-95 highway corridor in the State of Florida. Using logit curves, a sensitivity analysis is carried out to quantify the effect of traffic volume on the crash frequency. In addition to the crash frequency analysis, factors influencing the crash severity are also analyzed in an integrated manner for two metropolitan areas in the City of Jacksonville and Miami, Florida. Both frequency- and severity-focused analyses have led to several important conclusions. Results suggest that the variation in the hourly traffic volume significantly affects the crash occurrences for both aging and non-aging drivers depending on the geographical location; however, the crash occurrence for aging drivers is less sensitive to the flow than other age groups in congested locations. Results indicate that crash severity for all other age groups decrease on roadways with narrower shoulders and at night unlike those of aging drivers. Furthermore, driving at night on I-95 in Jacksonville seems to be problematic for both age classes whereas that risk is less for Miami locations. Higher roadway surface width also appears to increase the chance of having a severe crash for aging drivers. The DUI-influenced crashes have also been detected considerably high on the I-95 highway corridor in the City of Miami, Florida. This problem seems critical both in terms of crash frequency and severity. The proposed methodology can help transportation officials to understand the nature of the aging driver-involved crashes, and formulate better safety-oriented decisions.
Show less
Date Issued: 2016
Identifier: FSU_2016SU_Omidvar_fsu_0071N_13464
Format: Thesis

Title: Nanocarbon Foam/Polymer Composite.
Creator: Jamal, Muhamad Shahrizan, Zhang, Mei, Okoli, Okenwa, Shrivastava, Abhishek Kumar, Florida State University, College of Engineering, Department of Industrial and Manufacturing...
Show moreJamal, Muhamad Shahrizan, Zhang, Mei, Okoli, Okenwa, Shrivastava, Abhishek Kumar, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Weight of a material and the system formed by such material is a critical factor for many applications. Traditionally, engineering designed porous structures, typically honeycomb structures, have been utilized for weight critical applications. The goal of this thesis work is to utilize the material with the lightest weight to fabricate a new type of foam that is not only lightweight and strong, but also electrically as well as thermally conductive and with tunable elasticity. A carbon...
Show moreWeight of a material and the system formed by such material is a critical factor for many applications. Traditionally, engineering designed porous structures, typically honeycomb structures, have been utilized for weight critical applications. The goal of this thesis work is to utilize the material with the lightest weight to fabricate a new type of foam that is not only lightweight and strong, but also electrically as well as thermally conductive and with tunable elasticity. A carbon nanotube (CNT) based nanocarbon foam was fabricated by using poly (methyl methacrylate) spheres as a template to create engineered pores. The junctions between the CNTs are secured using nanocarbon via the oxidation and carbonization of polyacrylonitrile. The resulting low density foam exhibits robustness in structure, high elasticity, thermal stability, corrosion resistance and is also electrically as well as thermally conductive. The strength of the foam is further boosted with the infiltration of PMMA polymer. The resulting composite foam is still porous and has higher mechanical strength. The electrical conductivity of the composite foam is not affected despite the presence of PMMA.
Show less
Date Issued: 2016
Identifier: FSU_2016SU_Jamal_fsu_0071N_13228
Format: Thesis

Title: Conception and Development of 3D Sensing Using Wire-Shaped Hybrid PV Sensor as a Tool in TL-Based SHM System.
Creator: Yan, Jin, Okoli, Okenwa, Zheng, Jianping P., Dickens, Tarik J., Zhang, Mei, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing...
Show moreYan, Jin, Okoli, Okenwa, Zheng, Jianping P., Dickens, Tarik J., Zhang, Mei, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Structural Health Monitoring (SHM) systems have been studied by engineers and researchers for years [1-7], yet the applications of Triboluminescence (TL)-based SHM system for aerospace and civil structures are to a degree unexplored. Carbon fiber reinforced polymers composites (CFRP composites) have been increasingly applied in structure manufacturing due to their extraordinary mechanical properties. To realize the in-situ monitoring and minimize the effects of embedding damage sensors into...
Show moreStructural Health Monitoring (SHM) systems have been studied by engineers and researchers for years [1-7], yet the applications of Triboluminescence (TL)-based SHM system for aerospace and civil structures are to a degree unexplored. Carbon fiber reinforced polymers composites (CFRP composites) have been increasingly applied in structure manufacturing due to their extraordinary mechanical properties. To realize the in-situ monitoring and minimize the effects of embedding damage sensors into CFRP composites, TL crystals and carbon materials were used. Therefore, in this study, TL crystals (ZnS:Mn) acted as damage indicators, and solid-state all carbon photovoltaic sensors can form a sensory network to detect TL light and identify the damage/defects. Photovoltaic (PV) sensors introduced in this study focuses on using micro-sensor devices within the composite materials SHM system, which also explores the utilization of TL materials in these advanced materials systems. The conception of this 3D sensing system will be brought up in the first two chapters. The methods of fabricating different kinds of photovoltaic (PV) intrinsic sensors are described later in detail. The experimental results will focus on the effects of cell thickness, counter electrode (CE) type, and cell length on the cell light/electricity conversion efficiency. In the last part of research work, PV sensors have been tested under various light wavelengths using LEDs and TL crystals. Applications in industrial areas and future prospects will be discussed in the last chapter.
Show less
Date Issued: 2016
Identifier: FSU_2016SP_Yan_fsu_0071E_13184
Format: Thesis

Title: Fully Printable Single Layer Halide Perovskite/Peo Composite Thin Film LEDs.
Creator: Bade, Sri Ganesh Rohit, Yu, Zhibin, Liang, Zhiyong Richard, Wang, Hui, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Abstract/Description: Traditional light emitting diodes (LEDs) involve a complicated device structure with multiple layers stacked over one another. Such a complex, multilayered architecture restricts the application of diverse fabrication techniques. Earth-abundant organometal halide perovskites (Pero) have been well astounded for their appealing optoelectronic properties, low cost and solution processability which make them ideal candidates for large size photovoltaic and LED applications. The objective of this...
Show moreTraditional light emitting diodes (LEDs) involve a complicated device structure with multiple layers stacked over one another. Such a complex, multilayered architecture restricts the application of diverse fabrication techniques. Earth-abundant organometal halide perovskites (Pero) have been well astounded for their appealing optoelectronic properties, low cost and solution processability which make them ideal candidates for large size photovoltaic and LED applications. The objective of this thesis work is to fabricate Pero LED with uniform surface morphology, eliminating the multilayers with the help of Pero/Polyethylene oxide (PEO) composite thin film. Because of the simplicity in device architecture, this novel approach has the potential to surpass all the conceivable troubles involved in the fabrication of Pero LEDs. Preliminary results show a working device achieved by spin coating a thin film of Pero/PEO composite on ITO/glass serving as a bottom electrode and with In/Ga as the top electrode. Furthermore, fully printable and flexible Pero LEDs can be developed from this approach which can be scaled to large commercial roll to roll manufacturing.
Show less
Date Issued: 2016
Identifier: FSU_2016SU_Bade_fsu_0071N_13351
Format: Thesis

Title: Process Modeling and Study of Carbon Nanotube Dispersion in Aqueous Suspensions.
Creator: Yang, Ming-Chia (Dawn), Liang, Zhiyong Richard, Spainhour, Lisa, Vanli, Omer Arda, Zeng, Changchun Chad, Florida State University, College of Engineering, Department of...
Show moreYang, Ming-Chia (Dawn), Liang, Zhiyong Richard, Spainhour, Lisa, Vanli, Omer Arda, Zeng, Changchun Chad, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Establishing accurate processing models to characterize and study the suspension preparation for manufacturing carbon nanotube (CNT) thin films or buckypaper (BP) is a challenging task. Acquiring a fundamental understanding of quantifiable dispersion quality and time-dependent dispersion quality changes during and after the dispersion processes of CNT suspensions are critical for many suspension-based CNT manufacturing processes. In this research, a novel in-line dispersion quality monitoring...
Show moreEstablishing accurate processing models to characterize and study the suspension preparation for manufacturing carbon nanotube (CNT) thin films or buckypaper (BP) is a challenging task. Acquiring a fundamental understanding of quantifiable dispersion quality and time-dependent dispersion quality changes during and after the dispersion processes of CNT suspensions are critical for many suspension-based CNT manufacturing processes. In this research, a novel in-line dispersion quality monitoring system was developed. The monitoring was carried out using an integration of dynamic light scattering (DLS) and UV-Vis spectroscopy of a continuous flow during the CNT sonication dispersion process. This system can provide real-time monitoring of the quality of the suspension during the dispersion process and the stability of the suspension at post-dispersion stage. Monitoring the actual particle-size distribution can help determine the effective dispersion time and post-dispersion shelf life for potential use in process control and optimizing for scale-up manufacturing processes. We studied different CNT suspension systems, including MWNTs, SWNTs, graphene nanoplates, and their mixtures. For longer MWNTs with smaller diameters, the dispersion process achieved a steady agglomerate size around 100 nm with 40 minutes of sonication; for shorter and larger diameter MWNTs, due to their more packed agglomerate density, it took 60 minutes of sonication to reach the 100 nm agglomerate size. At the post-dispersion stage, the stability of CNT suspension showed nonlinear behavior due to the thermodynamic activity of CNT agglomerates. Under refrigerated storage condition, the increase of agglomerate size was reduced and the process of the CNT re-aggregation was prolonged by more than five times of the shelf life compared to the samples stored under room temperature. The study of dispersion of the carbon nanomaterial mixtures showed that MWNTs had helped the dispersion of SWNTs and graphene nanoplates throughout the sonication process to achieve a smaller agglomerate size after 75 minutes sonication. Quantitative quality baselines of the individual nanomaterials were established and used for controlling and optimizing the dispersion process and evaluating suspension stability. The dispersion mechanisms of different materials can be compared through the monitoring system.
Show less
Date Issued: 2016
Identifier: FSU_2016SU_Yang_fsu_0071E_13331
Format: Thesis

Title: Modified Natural Fibrils for Structural Hybrid Composites: Towards an Investigation of Textile Reduction.
Creator: Ufodike, Chukwuzubelu O., Dickens, Tarik J., Zhang, Mei, Shrivastava, Abhishek Kumar, Chatterjee, Jhunu, Florida State University, FAMU/FSU College of Engineering, Department of...
Show moreUfodike, Chukwuzubelu O., Dickens, Tarik J., Zhang, Mei, Shrivastava, Abhishek Kumar, Chatterjee, Jhunu, Florida State University, FAMU/FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Recently, the interest for renewable resources for fibers particularly of plant origin has been increasing. Reduction of use of traditional textile materials is now considered more critical due to the increasing environmental concern. Natural fibers are renewable, biodegradable, recyclable, and lightweight materials with high specific modulus, in competition with man-made fossil materials and fiberglass. Natural fibers are used for preparation of functionalized textiles to achieve smart and...
Show moreRecently, the interest for renewable resources for fibers particularly of plant origin has been increasing. Reduction of use of traditional textile materials is now considered more critical due to the increasing environmental concern. Natural fibers are renewable, biodegradable, recyclable, and lightweight materials with high specific modulus, in competition with man-made fossil materials and fiberglass. Natural fibers are used for preparation of functionalized textiles to achieve smart and intelligent properties. However, the incorporation of these fibers in composite systems has been challenging due to their hydrophilic nature. Nevertheless, the fact that these biodegradable materials can be manipulated at a nano-scale to complement desired objective and application has made them a favorable option. The idea behind this project is to explore ways to convert green waste to high value materials and to utilize natural building blocks to design textile reinforcement materials. In this work, cellulose nanofibrils (CNF) supplied from the University of Maine were hydrophobized by silylation and characterized using Fourier-Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, and Thermogravimetric analysis (TGA). Results from FTIR spectroscopy showed a formation of Si-O-C bonds, indicating better fiber-matrix adhesion. Raman spectroscopy showed disruption of hydrogen bonding which indicates interference of parallel nanocellulose fiber adhesion to neighboring fibrils. The TGA suggests that the thermal stability of the functionalized CNF is higher than that of the corresponding neat sample, which could be a result of stable Si bond formation. The raw materials (neat and functionalized) were encapsulated in a polystyrene matrix through a solvent and non-solvent precipitation process, and then extruded using single and dual heat processing. The extruded thin filaments were tested according to the ASTM D638 (tensile test of plastics). Results showed an increasing Ultimate Tensile Strength (UTS) and Elastic Modulus, with peak values attributed to the dual-heat processing up to 79% and 69% increase respectively at 5wt% loading. Further increase was seen at 10wt% loading up to 112MPa UTS, and modulus up to 10.7GPa for the dual-heat processing. The UTS increase is assumed to be a result of linear arrangement of CNF in the matrix during the extrusion process. The results revealed the strong reinforcing ability of CNF and their compatibility with thermoplastic matrix if functionalized.
Show less
Date Issued: 2016
Identifier: FSU_2016SP_Ufodike_fsu_0071N_13186
Format: Thesis

Title: Partial Gauss-Seidel Approach to Solve Large Scale Linear Systems.
Creator: Ghadiyali, Huzefa Shabbir, Park, Chiwoo, Shrivastava, Abhishek Kumar, Vanli, Omer Arda, Florida State University, College of Engineering, Department of Industrial and...
Show moreGhadiyali, Huzefa Shabbir, Park, Chiwoo, Shrivastava, Abhishek Kumar, Vanli, Omer Arda, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: With the advancement in technology and the constant need for optimization, a lot of resources are directed towards analyzing information collected. This information is in the form of large amounts of data that is gathered at every instant. The analysis of this data is often expressed in the form of linear system equations, where the size of the equations increases proportionally to the size of the data. Many methods have been developed to solve these systems. The main challenge in solving...
Show moreWith the advancement in technology and the constant need for optimization, a lot of resources are directed towards analyzing information collected. This information is in the form of large amounts of data that is gathered at every instant. The analysis of this data is often expressed in the form of linear system equations, where the size of the equations increases proportionally to the size of the data. Many methods have been developed to solve these systems. The main challenge in solving such large systems is to get an accurate solution along with computational eciency. The goal of this thesis is to develop a method which addresses both accuracy and computational eciency in solving large-scale linear systems. Our method will improve existing iterative techniques particularly for a linear equation system i.e. Ax = b where A is a positive denite and sparse full rank matrix. Linear systems of such kinds are commonly found in applications of Spatial regression. Hence, we will be using spatial data available publicly to test our method and present results of our method in this thesis.
Show less
Date Issued: 2016
Identifier: FSU_2016SP_Ghadiyali_fsu_0071N_13280
Format: Thesis

Title: Piezoresistivity of Mechanically Drawn Swcnt Thin Films: Mechanism and Optimizing Principle.
Creator: Obitayo, Waris, Liu, Tao, Shanbhag, Sachin, Zhang, Mei, Okoli, Okenwa, Oates, William S., Florida State University, College of Engineering, Department of Industrial and...
Show moreObitayo, Waris, Liu, Tao, Shanbhag, Sachin, Zhang, Mei, Okoli, Okenwa, Oates, William S., Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Carbon nanotubes (CNTs) are known to exhibit outstanding mechanical, electrical, thermal, and coupled electromechanical properties. CNTs can be employed towards the design of an innovative strain sensor with enhanced multifunctionality due to their load carrying capability, sensing properties, high thermal stability, and outstanding electrical conductivity. All these features indicate the prospect to use CNTs in a very wide range of applications, for instance, highly sensitive resistance-type...
Show moreCarbon nanotubes (CNTs) are known to exhibit outstanding mechanical, electrical, thermal, and coupled electromechanical properties. CNTs can be employed towards the design of an innovative strain sensor with enhanced multifunctionality due to their load carrying capability, sensing properties, high thermal stability, and outstanding electrical conductivity. All these features indicate the prospect to use CNTs in a very wide range of applications, for instance, highly sensitive resistance-type strain/force sensors, wearable electronics, flexible microelectronic devices, robotic skins, and in-situ structural health monitoring. CNT-based strain sensors can be divided into two different types, the individual CNT- based strain sensors and the ensemble CNT-based strain sensors e.g. CNT/polymer nanocomposites and CNT thin films. In contrast, to individual CNT-based strain sensors with very high gauge factor (GF) e.g. ~3000, the ensemble CNT-based strain sensors exhibit very low GFs e.g. for a SWCNT thin film strain sensor, GF is ~1. This research discusses the mechanisms and the optimizing principles of a SWCNT thin film piezoresistive sensor, and provide an experimental validation of the numerical/analytical investigations. The dependence of the piezoresistivity on key parameters like alignment, network density, bundle diameter (effective tunneling area), and SWCNT length is studied. The tunneling effect is significant in SWCNT thin films showing higher degrees of alignment, due to greater inter-tube distances between the SWCNTs as compared to random oriented SWCNT thin films. It can be concluded that SWCNT thin films featuring higher alignment would have a higher GF. On the other hand, the use of sparse network density which comprises of aligned SWCNTs can as well intensify the tunneling effect which can result to a further increase in the GF. In addition, it is well-known that percolation is greatly influenced by the geometry of the nanotubes e.g. bundle diameter and length. A study on the influence of bundle diameter of SWCNTs on the piezoresistivity behavior of mechanically drawn SWCNT thin films showed the best performance with an improved GF of ~10 when compared to the randomly oriented SWCNT thin films with GF of ~1. The non-linear piezoresistivity of the mechanically drawn SWCNT thin films is considered to be the main mechanism behind the high strain sensitivity. Furthermore, information about the average length and length distribution is very essential when examining the influence of individual nanotube length on the strain sensitivity. With that in mind, we use our previously developed preparative ultracentrifuge method (PUM), and our newly developed gel electrophoresis and simultaneous Raman and photolumiscence spectroscopy (GEP-SRSPL) to characterize the average length and length distribution of SWCNTs respectively.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Obitayo_fsu_0071E_12891
Format: Thesis

Title: Hierarchy Generation for Designing Assembly System for Product with Complex Liaison and Sub-Assembly Branches.
Creator: Jiang, Zhengqian, Wang, Hui, Okoli, Okenwa, Vanli, Omer Arda, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Abstract/Description: Manufacturers need to deploy their assembly systems in a timely manner to cope with expedited product development. Design of such responsive assembly systems consists of generation of assembly/subassembly operations and their hierarchies, operation-machine assignment, selections of machine types and quantities, and the material flow among machines. Exploration of all the feasible solutions to the assembly operations and their hierarchical relationships is vital to optimization of system...
Show moreManufacturers need to deploy their assembly systems in a timely manner to cope with expedited product development. Design of such responsive assembly systems consists of generation of assembly/subassembly operations and their hierarchies, operation-machine assignment, selections of machine types and quantities, and the material flow among machines. Exploration of all the feasible solutions to the assembly operations and their hierarchical relationships is vital to optimization of system designs. This research developed a theoretical framework based on a recursive algorithm to automatically generate all feasible and non-redundant assembly hierarchies efficiently, thereby investigating its impact on assembly system designs. Then this research further discussed the potential applications of the recursive framework in system optimization including joint determination of optimal assembly operations, operation-machine assignment, machine types and quantities, and the material flows among machines. The work was also extended to the optimization of assembly systems for the products with complex liaison relations and product families.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Jiang_fsu_0071N_12971
Format: Thesis

Title: Scalable Carbon Nanotube (CNT) Alignment: Process Development, Alignment Mechanisms and CNT/Carbon Fiber Hybrid Composite Applications.
Creator: Downes, Rebekah, Liang, Zhiyong (Richard), Vanli, Omer Arda, Spainhour, Lisa, Okoli, Okenwa, Maskell, Robin, Florida State University, College of Engineering, Department of...
Show moreDownes, Rebekah, Liang, Zhiyong (Richard), Vanli, Omer Arda, Spainhour, Lisa, Okoli, Okenwa, Maskell, Robin, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: To transfer the incredible properties, including ultrahigh tensile strength, Young's modulus, and electrical conductivity of an individual carbon nanotube (CNT) into composite applications, the constituent nanotubes need to possess adequate alignment, interfacial bonding and a high CNT volume fraction. Direct incorporation of the CNT films, or buckypaper, materials into carbon fiber laminated structures to manufacture hybrid composites is an effective approach to utilize the lightweight,...
Show moreTo transfer the incredible properties, including ultrahigh tensile strength, Young's modulus, and electrical conductivity of an individual carbon nanotube (CNT) into composite applications, the constituent nanotubes need to possess adequate alignment, interfacial bonding and a high CNT volume fraction. Direct incorporation of the CNT films, or buckypaper, materials into carbon fiber laminated structures to manufacture hybrid composites is an effective approach to utilize the lightweight, conductive and nanostructured nature of dense CNT networks for multifunctional applications of structural carbon fiber composites. This work studied the microstructure-property relationships of CNT networks when orientation is induced. The mechanical stretching method is shown to be scalable and effective for ultra-high alignment. A manufacturing technique of applying a viscous resin treatment before the stretching procedure is shown to allow up to 80% stretching strain and a resultant alignment fraction of 0.93. The resin acts as an effective load transfer media to substantially enhance the ductility for high stretching strain. The alignment characterization is carried out through Raman spectroscopy and X-ray diffraction methods that reveal the graphitic crystal structure of the film. The load transfer mechanisms and failure modes of aligned CNT composites are explored through high concentration CNT reinforced nanocomposites. Atomic resolution transmission electron microscopy (TEM) analysis reveals unusual CNT crystal packing and permit the observation of interesting structural features of the CNTs and their assemblages, including collapse, flattened packing, preferred stacking, folding and twisting phenomena, as well as CNT pullouts from bundles and the resin matrix. The intimate surface-to-surface contact areas between aligned and flattened nanotubes, driven by van der Waals interactions, give rise to a high density packing of the flattened CNTs in the nanocomposite, resembling a graphitic crystal material. Molecular dynamics (MD) simulations were performed through collaboration to model the packing structure and understand the dependence of density on the relative content of flattened nanotube and void space. Macroscopic modeling predictions illustrate how the alignment and volume fraction of the encompassed CNTs affect the stiffness of the overall composite. CNT thin films were integrated into carbon fiber (CF) prepreg composites to create hybrid composite materials with high CNT content through industry standard autoclave fabrication processing. Resin bleeding along the through-thickness direction was inhibited due to extra-low permeability, nano/micro dual-scale flow characteristics and high resin absorbing capacity of the CNT thin film in hybrid composites. CNT swelling effects and resin starvation phenomena are studied in relation to the amount and orientation of the CNT laminates. The flexural three-point bending results of the random and aligned CNT/CF hybrids exhibit an increased resistance to catastrophic failure even under repeated loading parameters as compared to the CF control samples. The dramatic improvements in both in-plane and through-thickness electrical conductivities demonstrate potential for both structural and multifunctional applications of the resultant hybrid composites.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Downes_fsu_0071E_12844
Format: Thesis

Title: Image Segmentation for Extracting Nanoparticles.
Creator: Allada, Kartheek, Park, Chiwoo, Shrivastava, Abhishek Kumar, Liu, Tao, Barbu, Adrian G. (Adrian Gheorghe), Florida State University, College of Engineering, Department of...
Show moreAllada, Kartheek, Park, Chiwoo, Shrivastava, Abhishek Kumar, Liu, Tao, Barbu, Adrian G. (Adrian Gheorghe), Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: With the advent of nanotechnology, nanomaterials have drastically improved our lives in a very short span of time. The more we can tap into this resource, the more we can change our lives for better. All the applications of nanomaterials depend on how well we can synthesize the nanoparticles in accordance with our desired shape and size, as they determine the properties and thereby the functionality of the nanomaterials. Therefore in this report, it is focused on how to extract the shape of...
Show moreWith the advent of nanotechnology, nanomaterials have drastically improved our lives in a very short span of time. The more we can tap into this resource, the more we can change our lives for better. All the applications of nanomaterials depend on how well we can synthesize the nanoparticles in accordance with our desired shape and size, as they determine the properties and thereby the functionality of the nanomaterials. Therefore in this report, it is focused on how to extract the shape of the nanoparticles from electron microscope images using image segmentation more accurately and more efficiently. By developing automated image segmentation procedure, we can systematically determine the contours of an assortment of nanoparticles from electron microscope images; reducing data examination and interpretation time substantially. As a result, the defects in the nanomaterials can be reduced drastically by providing an automated update to the parameters controlling the production of nanomaterials. The report proposes new image segmentation techniques that specifically work very effectively in extracting nanoparticles from electron microscope images. These techniques are manifested by imparting new features to Sliding Band Filter (SBF) method called Gradient Band Filter (GBF) and by amalgamating GBF with Active Contour Without Edges method, followed by fine tuning of μ (a positive parameter in Mumford-Shah functional). The incremental improvement in the performance (in terms of computation time, accuracy and false positives) of extracting nanoparticles is therefore portrayed by comparing image segmentation by SBF versus GBF, followed by comparing Active Contour Without Edges versus Active Contour Without Edges with the fusion of Gradient Band Filter (ACGBF). In addition we compare the performance of a new technique called Variance Method to fine tune the value of μ with fine tuning of μ based on ground truth, followed by gauging the improvement in the performance of image segmentation by ACGBF with fine tuned value of μ over ACGBF with an arbitrary value of μ.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Allada_fsu_0071N_12975
Format: Thesis

Title: Stretchlon Film Enhanced Fabriaction of Nanocomposites with the Resin Infusion Between Double Flexible Tooling.
Creator: Bhakta, Divyesh, Okoli, Okenwa, Liang, Zhiyong (Richard), Dickens, Tarik J., Olawale, David O., Florida State University, FAMU-FSU College of Engineering, Department of...
Show moreBhakta, Divyesh, Okoli, Okenwa, Liang, Zhiyong (Richard), Dickens, Tarik J., Olawale, David O., Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Recent studies have shown that the incorporation of carbon nanotubes (CNT) in to carbon fiber composite parts significantly increase mechanical as well as thermal properties. Polymer nanocomposites are polymer matrix composites that consist of reinforcements that have at least one dimension in the nanometer range. The polymer nanocomposite fabricated parts achieve greater mechanical, thermal, electrical and other properties with a low CNT reinforcement volume fraction. Nanocomposites achieve...
Show moreRecent studies have shown that the incorporation of carbon nanotubes (CNT) in to carbon fiber composite parts significantly increase mechanical as well as thermal properties. Polymer nanocomposites are polymer matrix composites that consist of reinforcements that have at least one dimension in the nanometer range. The polymer nanocomposite fabricated parts achieve greater mechanical, thermal, electrical and other properties with a low CNT reinforcement volume fraction. Nanocomposites achieve improved properties because of the higher properties of the nano-reinforcement and the high ratio of surface area to volume (aspect ratio) that provides greater interfacial interaction with the matrix. The fabrication of nanocomposites is primarily by the liquid composite molding (LCM) processes that can be complex process with many challenges. These challenges include poor CNT dispersion, poor bonding between resin and CNT, and blocking or filtration during the infusion process. The Resin Infusion between Double Flexible Tooling (RIDFT) however offers some advantages over the other LCM processes. The preservation and extended use of the mold can result in higher productivity and profit. In addition, a significantly lower pressure that translates to lower equipment cost, will be required to drive the high viscosity CNT-rich resin through the two-dimensional flow in a RIDFT process compared to the three-dimensional flow in the RTM. The RIDFT process may also be used for out-of-autoclave fabrication of composites from pre-pregs. The RIDFT process however has a number of fabrication issues militating against its wide use. These include long production cycle time due to the bottle neck associated with the setup time for cleaning the silicone sheet and the high cost of replacement of the flexible silicone membranes of the RIDFT machine. The introduction of Stretchlon Bagging 800 film may reduce the time that is expended on cleaning the silicone sheets and at the same time reduce the damage that is made to the silicone membranes. The goal of this thesis is to evaluate the performance of the Stretchlon bagging technique with the RIDFT process with the aim of significantly reducing the production cycle time as well as the production cost of composites and nanocomposites without adversely affecting the mechanical properties of the fabricated parts. The results show that the use of the Stretchlon bagging film resulted in reduction in the production cycle time of GFRP and CNT_GFRP parts of 32% and 42% respectively. It also resulted in production set-up (mold preparation) cost reduction for GFRP and CNT-GFRP parts of 49% and 72% respectively. It resulted in increased durability and service life of the silicon mold thereby helping to reduce the production cost. In addition, the use of the Stretchlon bagging film did not adversely affect the mechanical properties of the fabricated GFRP and CNT-GFRP parts. It resulted in an increase of 31.94% and 12.62% in the mean UTS of the GFRP and CNT-GFRP respectively. The Stretchlon film however resulted in reduction in the flexural properties of the fabricated GFRP and CNT-GFRP parts by 30.12% and 18.69% respectively. The use of the Stretchlon bagging film enhanced the in-plane properties of the fabricated parts by helping to increase the fiber volume fraction. The lower resin contents in the parts fabricated with the Stretchlon film may have had an adverse effect in the interlaminar properties resulting in lower flexural strengths. Furthermore, thermal analysis confirmed that there was no change in the glass transition (Tg) temperature of the fabricated parts. Parts fabricated with the Stretchlon bagging film also exhibited better surface finish than those fabricated without using the Stretchlon bagging film. In addition, a new design for the RIDFT with higher pressure capability for better quality parts (higher fiber volume fraction and lower void content) fabrication has been made. The new design also incorporates infrared lamp system for expedited curing of the composite parts in order to reduce the cycle time. Further work is however needed to optimize the RIDFT-Stretchlon film fabrication process for nanocomposites. A more detailed microscopy study needs to be performed to gain better insights into the reasons for the enhanced fiber volume content and in-plane properties achieved with the use of the Stretchlon film. In addition, the study needs to be repeated with functionalized CNTs to study the effects of functionalized CNTs on the fabricated parts, the silicon mold and the Stretchlon film. There is also the need to fabricate the new RIDFT design and optimize its performance for nanocomposite fabrication.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Bhakta_fsu_0071N_12806
Format: Thesis

Title: A Statistical Analysis of Effects of Test Methods on Spun Carbon Nanotube Yarn.
Creator: Veliky, Kenneth Blake, Liang, Zhiyong Richard, Zhang, Mei, Vanli, Omer Arda, Florida State University, College of Engineering, Department of Industrial and Manufacturing...
Show moreVeliky, Kenneth Blake, Liang, Zhiyong Richard, Zhang, Mei, Vanli, Omer Arda, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: Carbon nanotube (CNT) fibers are very promising materials for many applications. Strong interactions among individual CNTs could produce a dense yarn results in exceptional properties. These properties are used in the application of high-performance reinforcement for composites. As the reinforcement, the primary function is to provide outstanding load bearing capability. Currently literatures use a variety of measurement techniques and gauge lengths that have not been uniform for CNT yarn...
Show moreCarbon nanotube (CNT) fibers are very promising materials for many applications. Strong interactions among individual CNTs could produce a dense yarn results in exceptional properties. These properties are used in the application of high-performance reinforcement for composites. As the reinforcement, the primary function is to provide outstanding load bearing capability. Currently literatures use a variety of measurement techniques and gauge lengths that have not been uniform for CNT yarn tests. The need for a standardized testing method for characterization is necessary in generating reproducible and comparable data for CNT yarn or fiber materials. In this work, the strength of CNT fibers was characterized using three different types of tensile test method: the film and fiber test fixtures from dynamics mechanic analysis (DMA), and TS 600 tensile fixture. Samples that underwent the film and TS 600 tensile fixture were attached with a thick paper tabbing methodology based on ASTM standard D3379. As for the fiber fixture was performed with the test material attached directly to the fixture based on the fiber test instruction from TA Instrument. The results of the three different methods provided distinct variance in stress, strain, and modulus. A design of experiment (DoE) was established and performed on the DMA film fixture as determined from the preliminary experiment. The DoE was successful in quantifying the critical parameters' ranges that attributed to standard deviation of average stress. These parameters were then tested on 30 more samples with an improved additive manufactured tab. The results significantly decreased all mechanical testing parameters' standard deviations. Most importantly, the results prove the probability of a valid gauge break increased to more than 400%.
Show less
Date Issued: 2015
Identifier: FSU_2015fall_Veliky_fsu_0071N_12979
Format: Thesis

Title: Biocompatible Poly (Lactic Acid)/Thermoplastic Polyurethane Blends.
Creator: Burkett, Mary K., Department of Industrial and Manufacturing Engineering
Abstract/Description: In order to create a polymer that has the morphology and structure to be used for industrial applications, the foamability of the PLA must be improved by blending. Blends were made in specific ratios of 80/20, 50/50, and 20/80. Next, the blends were extruded and injected into molds for testing. The mechanical and thermal properties of the blends were tested using the tensile test and the DSC. The morphology was also observed using the SEM. Finally, a series of stock materials were created to...
Show moreIn order to create a polymer that has the morphology and structure to be used for industrial applications, the foamability of the PLA must be improved by blending. Blends were made in specific ratios of 80/20, 50/50, and 20/80. Next, the blends were extruded and injected into molds for testing. The mechanical and thermal properties of the blends were tested using the tensile test and the DSC. The morphology was also observed using the SEM. Finally, a series of stock materials were created to be used for melt-electrospinning or 3D printing.
Show less
Date Issued: 2015
Identifier: FSU_migr_uhm-0526
Format: Thesis

Title: A Study on Sonication Dispersion Parameters for Batchproduction of Carbon Nanotube Buckypaper.
Creator: Vargas, Emily Anne, Department of Industrial and Manufacturing Engineering
Abstract/Description: Buckypaper (BP) is a macroscopic aggregate of carbon nanotubes. More specifically, it is an easy-to-handle thin film formed from carbon nanotube networks. Buckypaper contains valuable high mechanical strength, electrical, and thermal conductivity due to their nanoscale dimension and unique structural network. Application examples of buckypaper include for fire and lightning protection, aerospace structures, armor plating, artificial muscles, miniaturization of electrical connections, and etc....
Show moreBuckypaper (BP) is a macroscopic aggregate of carbon nanotubes. More specifically, it is an easy-to-handle thin film formed from carbon nanotube networks. Buckypaper contains valuable high mechanical strength, electrical, and thermal conductivity due to their nanoscale dimension and unique structural network. Application examples of buckypaper include for fire and lightning protection, aerospace structures, armor plating, artificial muscles, miniaturization of electrical connections, and etc. The current batch-production method has its own associated limitations and problems, including long process time, cost effectiveness, as well as spilling and improper sonication operation. This research will focus on the analysis of sonication time, examining an effective filtration model that will produce buckypaper at effective rates, and the effect of oven drying on the buckypaper, without sacrificing its conducive, electric, and strength properties. The technical approach used in this work is to study the effect of varying the sonication process time on the quality and properties of the resultant buckypaper samples. During this experiment, buckypaper was created using high, medium, and low sonication times, as well as samples were placed in the oven and compared to those that were not. The study proves that lower sonication time does not prove to be ideal in the maintaining the properties of the buckypaper. The resultant buckypaper did not yield good results due to the tendency of carbon nanotubes to agglomerate with short sonication dispersion time. Additionally, samples that were not placed in the oven after water and methanol baths still proved to have large amounts of surfactant left over, affecting the density and properties of the buckypaper. Poor dispersion and high residual surfactant lead to a decrease in functional properties such as mechanical, electrical, and thermodynamic of the buckypaper. Further investigation into applying those batch-production parameters to the continuous manufacturing process is necessary.
Show less
Date Issued: 2015
Identifier: FSU_migr_uhm-0585
Format: Thesis

Title: Topological and Electrical Properites of Carbon Nanotube Networks.
Creator: Li, Min-Yang, Liang, Zhiyong Richard, Park, Chiwoo, Andrei, Petru, Zhang, Mei, Florida State University, College of Engineering, Department of Industrial and Manufacturing...
Show moreLi, Min-Yang, Liang, Zhiyong Richard, Park, Chiwoo, Andrei, Petru, Zhang, Mei, Florida State University, College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: A major challenge to the study of the structure-property relationship of carbon nanotube (CNT) networks is to characterize the complex nanostructure with complicated nanoscale contacts and pore structures. An image-based characterization methodology was proposed to extract CNT network information directly from scanning electron microscope (SEM) images of various CNT thin films to characterize critical topological factors including bundle size, diameter, and orientation from the CNT networks....
Show moreA major challenge to the study of the structure-property relationship of carbon nanotube (CNT) networks is to characterize the complex nanostructure with complicated nanoscale contacts and pore structures. An image-based characterization methodology was proposed to extract CNT network information directly from scanning electron microscope (SEM) images of various CNT thin films to characterize critical topological factors including bundle size, diameter, and orientation from the CNT networks. This approach provided high-fidelity and fast analysis of CNT network structures with low false positive rate (FPR) of ~3% and ~90% accuracy in most of our case studies. We applied the new approach to study different networks of multi-walled carbon nanotube (MWNT), single-walled carbon nanotube (SWNT), MWNT-SWNT mixed, and stretched MWNTs with different CNT alignments, which revealed the electrical conductivity-structure relationships of MWNT networks. On the other hand, controlling the transfer of electrical and mechanical properties of nanotubes into nanocomposites remains one of the major challenges due to the lack of adequate measurement systems to quantify the variations in bulk properties while the nanotubes were used as the reinforcement material. One-way analysis of variance (ANOVA) on thickness and conductivity measurements were conducted. By analyzing the data collected from both experienced and inexperienced operators, we found some operation details users might overlook that resulted in variations, since conductivity measurements of CNT thin films are very sensitive to thickness measurements. In addition, we demonstrated how issues in measurements damaged samples and limited the number of replications resulting in large variations in the electrical conductivity measurement results. Based on this study, we proposed a faster, more reliable approach to measure the thickness of CNT thin films that operators can follow to make these measurement processes less dependent on operator skills.
Show less
Date Issued: 2015
Identifier: FSU_2016SU_Li_fsu_0071E_13311
Format: Thesis

Title: Laser Processing for Manufacturing Nanocarbon Materials.
Creator: Van, Hai Hoang, Zhang, Mei, Li, Hui, Okoli, Okenwa, Liang, Zhiyong Richard, Liu, Tao, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and...
Show moreVan, Hai Hoang, Zhang, Mei, Li, Hui, Okoli, Okenwa, Liang, Zhiyong Richard, Liu, Tao, Florida State University, FAMU-FSU College of Engineering, Department of Industrial and Manufacturing Engineering
Show less
Abstract/Description: CNTs have been considered as the excellent candidate to revolutionize a broad range of applications. There have been many method developed to manipulate the chemistry and the structure of CNTs. Laser with non-contact treatment capability exhibits many processing advantages, including solid-state treatment, extremely fast processing rate, and high processing resolution. In addition, the outstanding monochromatic, coherent, and directional beam generates the powerful energy absorption and the...
Show moreCNTs have been considered as the excellent candidate to revolutionize a broad range of applications. There have been many method developed to manipulate the chemistry and the structure of CNTs. Laser with non-contact treatment capability exhibits many processing advantages, including solid-state treatment, extremely fast processing rate, and high processing resolution. In addition, the outstanding monochromatic, coherent, and directional beam generates the powerful energy absorption and the resultant extreme processing conditions. In my research, a unique laser scanning method was developed to process CNTs, controlling the oxidation and the graphitization. The achieved controllability of this method was applied to address the important issues of the current CNT processing methods for three applications. The controllable oxidation of CNTs by laser scanning method was applied to cut CNT films to produce high-performance cathodes for FE devices. The production method includes two important self-developed techniques to produce the cold cathodes: the production of highly oriented and uniformly distributed CNT sheets and the precise laser trimming process. Laser cutting is the unique method to produce the cathodes with remarkable features, including ultrathin freestanding structure (~200 nm), greatly high aspect ratio, hybrid CNT-GNR emitter arrays, even emitter separation, and directional emitter alignment. This unique cathode structure was unachievable by other methods. The developed FE devices successfully solved the screening effect issue encounter by current FE devices. The laser-control oxidation method was further developed to sequentially remove graphitic walls of CNTs. The laser oxidation process was directed to occur along the CNT axes by the laser scanning direction. Additionally, the oxidation was further assisted by the curvature stress and the thermal expansion of the graphitic nanotubes, ultimately opening (namely unzipping) the tubular structure to produce GNRs. Therefore the developed laser scanning method optimally exploited the thermal laser-CNT interaction, successfully transforming CNTs into 2D GNRs. The solid-state laser unzipping process effectively addressed the issues of contamination and scalability encountered by the current unzipping methods. Additionally, the produced GNRs were uniquely featured with the freestanding structure and the smooth surfaces. If the scanning process was performed in an inert environment without the appearance of oxygen, the oxidation of CNTs would not happen. Instead, the greatly mobile carbon atoms of the heated CNTs would reorganize the crystal structure, inducing the graphitization process to improve the crystallinity. Many observations showing the structural improvement of CNTs under laser irradiation has been reported, confirming the capability of laser to heal graphitic defects. Laser methods were more time-efficient and energy-efficient than other annealing methods because laser can quickly heat CNTs to generate graphitization in less than one second. This subsecond heating process of laser irradiation was more effective than other heating methods because it avoided the undesired coalescence of CNTs. In my research, the laser scanning method was applied to generate the graphitization, healing the structural defects of CNTs. Different from the reported laser methods, the laser scanning directed the locally annealed areas to move along the CNT axes, migrating and coalescencing the graphitic defects to achieve better healing results. The critical information describing the CNT structural transformation caused by the moving laser irradiation was explored from the successful applications of the developed laser method. This knowledge inspires an important method to modify the general graphitic structure for important applications, such as carbon fiber production, CNT self-assembly process and CNT welding. This method will be effective, facile, versatile, and adaptable for laboratory and industrial facilities.
Show less
Date Issued: 2015
Identifier: FSU_2016SP_Van_fsu_0071E_12881
Format: Thesis

Title: Cast Forming of Carbon Nanotube Networks Using Paraffin.
Creator: Veliky, Kenneth, Department of Industrial and Manufacturing Engineering
Abstract/Description: Carbon nanotube thin film, or buckypaper, is one of the most revolutionary materials in the 21st century. Mechanical, electrical, and thermodynamic properties that can only be dreamed of in science fiction novels are now within reach in the science and technology field. As amazing as this material is, there exist problems within the manufacturability of buckypaper. Problems such as process time, scalability, and cost effectiveness to produce a sample hinder the ability to produce buckypaper...
Show moreCarbon nanotube thin film, or buckypaper, is one of the most revolutionary materials in the 21st century. Mechanical, electrical, and thermodynamic properties that can only be dreamed of in science fiction novels are now within reach in the science and technology field. As amazing as this material is, there exist problems within the manufacturability of buckypaper. Problems such as process time, scalability, and cost effectiveness to produce a sample hinder the ability to produce buckypaper to the commercial market. This research effort is to study, through experimentation, a new approach to create buckypaper using cast formation of a carbon nanotube network while in a paraffin suspension. Because current nanotube dispersion and filtration methods, such as sonication can produce high costs and slow processing times, the need for new buckypaper manufacturing method is evident. During this experiment, buckypaper was created using two methods for dispersion, the first was a mechanic mixing method and the second was the traditional method of sonication. The study proves that the use of paraffin as the dispersion and flow medium does not provide ideal results to eliminate steps such as sonication and filtration. The resultant buckypaper through mixing did not yield good results due to the nature of carbon nanotube's tendency to agglomerate while heat is applied during the dispersion process. Poor dispersion leads to a decrease in functional properties such as mechanical, electrical or thermodynamic. It is conclusive that further investigation into this method is necessary.
Show less
Date Issued: 2014
Identifier: FSU_migr_uhm-0361
Format: Thesis

Title: Auxetic Polyurethane Foam: Manufacturing and Processing Analysis.
Creator: Jahan, Md. Deloyer, Zeng, Changchun, Liang, Zhiyong, Vanli, Arda, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Materials with negative Poisson's ratio are referred to as auxetic materials. They are different from conventional materials in their deformation behavior when responding to external stresses. The cross-section of the materials widens in the lateral direction when being stretched in the longitudinal direction and becomes narrower when being compressed longitudinally. While a number of natural auxetic materials exist, most auxetic materials are synthetic. They show interesting properties and...
Show moreMaterials with negative Poisson's ratio are referred to as auxetic materials. They are different from conventional materials in their deformation behavior when responding to external stresses. The cross-section of the materials widens in the lateral direction when being stretched in the longitudinal direction and becomes narrower when being compressed longitudinally. While a number of natural auxetic materials exist, most auxetic materials are synthetic. They show interesting properties and have potential in several important applications. Auxetic materials exhibit better mechanical properties than conventional materials such as enhanced indentation resistance, shear resistance, toughness, damping and energy absorption capacity, sound absorption, variable permeability and capability of producing complex curvature. These properties are beneficial in a wide range of applications including personal protective equipments, sound absorbers, packaging, smart filtration, drug delivery, tissue scaffolding, seat cushioning, etc. A wide range of auxetic materials has been synthesized. They include different polymers, metals, composites and ceramics. Among these, auxetic polyurethane (PU) foam is one of the most widely studied types of auxetic materials. Auxetic PU foams are usually fabricated by altering the microstructure of conventional foams and the unusual mechanical properties originate from the deformation characteristics of the microstructures. Three most important processing parameters in fabricating auxetic PU foam that dictate auxetic behavior are processing temperature, heating time and volumetric compression ratio. This study addresses several important issues in the manufacturing and characterization of auxetic PU foam. First, an improved automatic measuring technique has been developed to determine Poisson's ratio of auxetic PU foam. The technique involves development of a Matlab based image processing program. The second part of the study includes an experimental design approach to identify significant processing parameters followed by optimization of those processing parameters in fabrication of auxetic PU foam. A split-plot factorial design has been selected for screening purpose. Response Surface Methodology (RSM) has been utilized to optimize the processing parameters in fabrication of auxetic PU foam. Two different designs named Box-Behnken and I-optimal designs have been employed for this analysis. The results obtained by those designs exhibit that I-optimal design provides more accurate and realistic results than Box-Behnken design when experiments are performed in split-plot manner. Finally, a near stationary ridge system is obtained by optimization analysis. As a result a set of operating conditions are obtained that produces similar minimum Poisson's ratio in auxetic PU foam.
Show less
Date Issued: 2014
Identifier: FSU_migr_etd-9011
Format: Thesis

Title: Standardization of Buckypaper Composite Actuator Fabrication Process and Improvement of Force Generation.
Creator: DeGraff, Joshua, Liang, Zhiyong, Vanli, Arda, Zeng, Chad, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: The Buckypaper/Nafion composite actuator (BCA) is promising for lightweight and micro-robotic system applications. Lightweight BCA provides an energy-efficient and flexible design to achieve muscle-like actuation for micro-actuator applications. The BCA encompasses of a solid Nafion electrolyte stacked between two conductive carbon nanotube thin thins or Buckypaper (BP) sheets. As an ionic electro-active polymer (iEAP), Nafion's response to an electrical signal is similar to the...
Show moreThe Buckypaper/Nafion composite actuator (BCA) is promising for lightweight and micro-robotic system applications. Lightweight BCA provides an energy-efficient and flexible design to achieve muscle-like actuation for micro-actuator applications. The BCA encompasses of a solid Nafion electrolyte stacked between two conductive carbon nanotube thin thins or Buckypaper (BP) sheets. As an ionic electro-active polymer (iEAP), Nafion's response to an electrical signal is similar to the electrochemical response of biological muscles. The adhesion between the electrolyte film and the electrode materials is critical to the actuator performance. BCA manufacturing avoids the complexities of repetitive metallic plating, as BP supplies a high surface area film of conductive carbon nanotubes. Since the actuator's charging occurs where the constituent materials come in contact, a standard manufacturing process needs to be developed to ensure repeatability. This research includes two focuses. The first focus pertains to optimizing the ion-exchange processes that improve Nafion's ionic transport properties. The second focus is to strengthening the interaction between Nafion and Buckypaper, which will ensure effective charge accumulation at the interface and improve the BCA's mechanical properties relevant to force exertion. The research presents a novel BCA manufacturing approach to achieve excellent repeatability and significantly improves the BCA's mechanical properties
Show less
Date Issued: 2014
Identifier: FSU_migr_etd-8765
Format: Thesis

Title: In-Situ Triboluminescent Optical Fiber Sensor for Real-Time Damage Monitoring in Cementitious Composites.
Creator: Olawale, David Oluseun, Okoli, Okenwa I., Sobanjo, John O., Liu, Tao, Liang, Zhiyong, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Triboluminescent-based sensor systems have the potential to enable in-situ and distributed structural health monitoring of composite structures. Inability to effectively capture and transmit optical signals generated within opaque composites like concrete and carbon fiber reinforced polymers have however greatly limited their use. This problem has been solved by developing the bio-inspired in-situ triboluminescent optical fiber (ITOF) sensor. This sensor has the potential for wireless, in...
Show moreTriboluminescent-based sensor systems have the potential to enable in-situ and distributed structural health monitoring of composite structures. Inability to effectively capture and transmit optical signals generated within opaque composites like concrete and carbon fiber reinforced polymers have however greatly limited their use. This problem has been solved by developing the bio-inspired in-situ triboluminescent optical fiber (ITOF) sensor. This sensor has the potential for wireless, in-situ, real-time and distributed (WIRD) damage monitoring. Its integrated sensing (triboluminescent thin film) and transmission (polymer optical fiber) components convert the energy from damage events like impacts and crack propagation into optical signals that are indicative of the magnitude of damage in composites. Utilizing the triboluminescent (TL) property of ZnS-Mn, the ITOF sensor has been successfully fabricated. Key design parameters were evaluated to develop a sensor with enhanced damage sensing capability. Sensor's performance was then characterized with Raman spectroscopy, field emission scanning electron microscopy (FESEM) and dynamic mechanical analysis (DMA). Flexural tests were also carried out to evaluate the damage sensing performance of the sensor before integrating into unreinforced concrete beams to create triboluminescent multifunctional cementitious composites (TMCC) with in-situ damage monitoring capabilities like biological systems. Results show that the ZnS-Mn in the epoxy coating of the ITOF sensor does not degrade the thermo-mechanical properties of the composite system. Raman spectroscopy indicates that the ZnS-Mn crystals retained their physical and chemical properties after undergoing the sensor fabrication process. Enhanced side-coupling of TL signals from the ITOF coating into the polymer optical fiber (POF) was achieved with TL thin film coating on POF. This makes distributed sensing possible when the length of the POF is coated with TL thin film. A new approach to damage characterization using TL emission profiles was employed with the TMCC. Three modes of sensor excitation in the TMCC were identified indicative of sensor's ability to sense crack propagation through the beam even when not in contact with the crack. FESEM analysis indicated that fracto-triboluminescence was responsible for the TL signals observed at beam failure. The TL profile analysis promises to facilitate better understanding of crack propagation in composite structural materials.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7954
Format: Thesis

Title: Assessment of Triboluminescent Materials for Intrinsic Health Monitoring of Composite Damage.
Creator: Dickens, Tarik J., Okoli, Okenwa, Dalal, Naresh, Liu, Ted, Liang, Richard, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Advanced composites offer robust mechanical properties and are widely used for structural applications in the aerospace, marine, defense and transportation industries. However, the inhomogenous nature of composite materials leaves them susceptible to problematic failure; thus the development of a means for detecting failure is imperative. Damage occurs when a load is applied and a distortion of the solid material results in deformation. This process also results in straining of the material....
Show moreAdvanced composites offer robust mechanical properties and are widely used for structural applications in the aerospace, marine, defense and transportation industries. However, the inhomogenous nature of composite materials leaves them susceptible to problematic failure; thus the development of a means for detecting failure is imperative. Damage occurs when a load is applied and a distortion of the solid material results in deformation. This process also results in straining of the material. Strain, however, is a physical result of work being performed on a solid material making energy the commonality among all failure mechanisms. This study investigated the feasibility of using Triboluminescent zinc-sulphide manganese (ZnS:Mn) phosphors concentrated in vinyl ester resin for damage monitoring of polymer composites under flexural loading. These particulates react to straining or fracturing by emitting light of varied luminous intensity and detecting the crack initiation presently leading to catastrophic failure(s). Unreinforced vinyl ester resins and fiber-reinforced composite beams incorporated 5 - 50 % wt. concentrations of TL fillers, and were subjected to three-point bend tests. The intent of flexural testing was to observe the transient response of triboluminescence (TL) in both two- and three-phase composite systems throughout the failure cycle of notched beams, while changing the geometric constraints. Results indicate TL crystals emit light at various intensities corresponding to crystal concentration, the notch-length and imminent matrix fracture. The fracturing or deformation energy was estimated by the method of J-integral with varied notch-lengths, where a lower threshold for excitation was found to be approximately <2 J/m^2, far below its critical fracture energy (~ 3 & 7 J/m^2). Consequently, concentrated samples showed nearly 50 % reductions of mechanical moduli due to high loading levels, which subsequently affected the Triboluminescent response. As a result, an optimal 6 % vol. of TL particulates was chosen for further study and exhibited significant signal-to-noise response. Scanning electron microscopy (SEM) revealed particulate inclusions with shearing bands and semblance of particle to resin adhesion, as well as, cases of micro-cracking in reinforced samples. Despite significant parasitic affect to mechanical properties, the luminescent properties of TL occur at rupture for unreinforced composites. The cases of TL concentrated reinforced composites show detection of localized matrix phenomenon which are related to the material response and incurring internal strain-energy prior to any catastrophic failure. This indicates that TL in composite systems has the potential to detect micro-failures (micro-cracks) related to the weak matrix component. The triboluminescent signal was simulated as a rate-dependent model considering the load profile of the composite beam is known.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7772
Format: Thesis

Title: Characterizing the Single-Walled Carbon Nanotube Dispersions: Novel Methods Development and Their Applications.
Creator: Xiao, Zhiwei, Liu, Tao, Ramakrishnan, Subramanian, Liang, Zhiyong, Guan, Jingjiao, Zhang, Mei, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Single-walled carbon nanotubes (SWCNTs) thin films exhibit great potential in various applications thanks to their extraordinary physical and mechanical properties. However, to fully take advantage of their superior properties there are still several barriers to be overcome. On one hand, SWCNTs are rarely found as isolated individual tubes, which makes them very difficult to exfoliate and disperse. On the other hand, SWCNTs are not with perfect defect-free chemical structure, which can...
Show moreSingle-walled carbon nanotubes (SWCNTs) thin films exhibit great potential in various applications thanks to their extraordinary physical and mechanical properties. However, to fully take advantage of their superior properties there are still several barriers to be overcome. On one hand, SWCNTs are rarely found as isolated individual tubes, which makes them very difficult to exfoliate and disperse. On the other hand, SWCNTs are not with perfect defect-free chemical structure, which can severely degrade the intrinsic properties of the pristine SWCNTs and thus deteriorate the various SWCNT based applications. In many cases, when people perform chemical functionalization to SWCNTs, they have to find a balance between the improvement of the dispersability and compatibility of SWCNTs and the degradation of the intrinsic properties of SWCNTs. Therefore, it is crucial to have an easy-to-use and reliable way to characterize and quantify the corresponding structural information of SWCNT in dispersion such as bundle size, bundling state, defect density, etc. Two different techniques for in-situ structural characterization of SWCNTs in dispersion have been developed. The Preparative Ultracentrifuge Method (PUM) combined with dynamic light scattering (DLS) technique provides us an approach to investigate the bulk averaged SWCNT bundle size in dispersion. The Simultaneous Raman Scattering and Photoluminescence (SRSPL) technique allows us to study the bundling state/degree of exfoliation of SWCNT in dispersion. Based on the 1D exciton diffusion model, we can also use the SRSPL technique to estimate the defect density of SWCNTs in dispersion. The application of PUM and SRSPL has been demonstrated in studying the structural changes of SWCNT dispersion under different processing (sonication and ultracetrifugation) conditions. It revealed the exfoliation mechanism of SWCNT under sonication technique. Moreover, the developed PUM characterization techniques were further applied to study the interactions between SWCNT and polyacrylonitrile (PAN) homo- and copolymers. On the basis of the established PUM and SRSPL characterization methods, my proposed work focuses on an in-depth understanding of the effects of bundling states and defect density on the electrical and mechanical properties of SWCNT thin films. The detailed proposed tasks include: 1) improve the current physical model for quantifying defect density; 2) prepare and characterize the SWCNT dispersions with controlled bundle size and defect density; 3) fabricate and characterize the electrical and mechanical properties of SWCNT thin films to elucidate the effects of bundling state and defect density of SWCNTs in the dispersion.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7670
Format: Thesis

Title: Recycling High-Performance Carbon Fiber Reinforced Polymer Composites Using Sub-Critical and Supercritical Water.
Creator: Knight, Chase C., Zeng, Changchun, Zhang, Chuck, Chella, Ravindran, Liang, Richard, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Carbon fiber reinforced plastics (CFRP) are composite materials that consist of carbon fibers embedded in a polymer matrix, a combination that yields materials with properties exceeding the individual properties of each component. CFRP have several advantages over metals: they offer superior strength to weight ratios and superior resistance to corrosion and chemical attack. These advantages, along with continuing improvement in manufacturing processes, have resulted in rapid growth in the...
Show moreCarbon fiber reinforced plastics (CFRP) are composite materials that consist of carbon fibers embedded in a polymer matrix, a combination that yields materials with properties exceeding the individual properties of each component. CFRP have several advantages over metals: they offer superior strength to weight ratios and superior resistance to corrosion and chemical attack. These advantages, along with continuing improvement in manufacturing processes, have resulted in rapid growth in the number of CFRP products and applications especially in the aerospace/aviation, wind energy, automotive, and sporting goods industries. Due to theses well-documented benefits and advancements in manufacturing capabilities, CFRP will continue to replace traditional materials of construction throughout several industries. However, some of the same properties that make CFRP outstanding materials also pose a major problem once these materials reach the end of service life. They become difficult to recycle. With composite consumption in North America growing by almost 5 times the rate of the US GDP in 2012, this lack of recyclability is a growing concern. As consumption increases, more waste will inevitably be generated. Current composite recycling technologies include mechanical recycling, thermal processing, and chemical processing. The major challenge of CFRP recycling is the ability to recover materials of high-value and preserve their properties. To this end, the most suitable technology is chemical processing, where the polymer matrix can be broken down and removed from the fiber, with limited damage to the fibers. This can be achieved using high concentration acids, but such a process is undesirable due to the toxicity of such materials. A viable alternative to acid is water in the sub-critical and supercritical region. Under these conditions, the behavior of this abundant and most environmentally friendly solvent resembles that of an organic compound, facilitating the breakdown of the polymer matrix. To date, very few studies have been reported in this area and the studies thus far have only focused on small scale feasibility and have only shown the recovery of random fibers. The goal of this research is to advance the knowledge in the field of sub-critical and supercritical fluid recycling by providing fundamental information that will be necessary to move this process forward to an industrial scale. This dissertation work consists of several phases of studies. In the first phase of this research, the feasibility of recycling woven CFRP was established on a scale approximately 30 times larger than previously reported. The industrial relevance was also conveyed, as the process was shown to remove up 99% of a highly cross-linked resin from an aerospace grade composite system with 100% retention of the single filament tensile strength and modulus whilst also retaining the highly valuable woven fiber structure. The second phase of research demonstrated the power of this technology to recycle multi-layer composites and provide the ability to reuse the highly valuable materials. Up to 99% resin elimination was achieved for a woven 12-layer aerospace grade composite. The recycled woven fabric layers, with excellent retention of the fiber architecture, were directly reused to fabricate reclaimed fiber composites (RFC). Manufacturing issues associated with the use of the recycled fiber were investigated. Several fabrication technologies were used to fabricate the composite, and the composites show moderate short beam shear strength and may be suitable for certain industrial applications. Moreover, fresh composites were also recycled, recovered, and reused to investigate the retention of flexural properties of the fibers after recycling. Up to 95% of the flexural strength and 98% of the flexural modulus was retained in the reclaimed fiber composites. The recycled resin residual can be incorporated into fresh resin and cured, demonstrating a near complete recycling loop. After showing the feasibility and power of this technology, the third phase of the study was focused on the fundamentals on the degradation of highly cross-linked polymer network by sub- and near-critical water. A methodology framework was established to study the apparent kinetics of the degradation of epoxy in sub-critical water. The reaction rate was modeled by a phenomenological rate model of nth order, and the rate constant was modeled by taking into account of the contributions of important physical parameters, e.g., pressure, temperature and dielectric constants. The applicability of the established model to describe the degradation kinetics was confirmed by the validation runs. This model is a suitable starting point to gain the knowledge required for eventual industrial process design. The final phase of this research consisted of a preliminary foray into investigating the economic feasibility of this technology. A process model was designed around a reactor which was sized according to considerations of industrial relevancy. The simulation of the process was done using Aspen Plus, powerful and comprehensive process simulation software. Economic analysis of this pseudo-realistic process suggested that such technology was economically viable and competitive comparing to other recycling technologies. In summary, this dissertation work represents the first comprehensive investigation on recycling aerospace-grade, multilayer woven fabric composites using supercritical and sub-critical water. The fundamental knowledge gained and process technology developed during this research is anticipated to play an important role in advancing this recycling technology toward potential adoption and implementation by the recycling and composite industry.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7450
Format: Thesis

Title: Processing-Structure-Property Relationships of Carbon Nanotube and Nanoplatelet Enabled Piezoresistive Sensors.
Creator: Luo, Sida, Liu, Tao, Brooks, James, Zhang, Chuck, Zhang, Mei, Shanbhag, Sachin, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Individual carbon nanotubes (CNTs) possess excellent piezoresistive performance, which is manifested by the significant electrical resistance change when subject to mechanical deformation. In comparison to individual CNTs, the CNT thin films, formed by a random assembly of individual tubes or bundles, show much lower piezoresistive sensitivity. Given the progress made to date in developing CNT ensemble based-piezoresistive sensors, the related piezoresistive mechanism(s) are still not well...
Show moreIndividual carbon nanotubes (CNTs) possess excellent piezoresistive performance, which is manifested by the significant electrical resistance change when subject to mechanical deformation. In comparison to individual CNTs, the CNT thin films, formed by a random assembly of individual tubes or bundles, show much lower piezoresistive sensitivity. Given the progress made to date in developing CNT ensemble based-piezoresistive sensors, the related piezoresistive mechanism(s) are still not well understood. The crucial step to obtain a better understanding of this issue is to study the effects of CNT structure in the dispersion on the piezoresistivity of CNT ensemble based-piezoresistive sensors. To reach this goal, my Ph.D. research first focuses on establishing the processing-structure-property relationship of SWCNT thin film piezoresistive sensors. The key accomplishment contains: 1) developing the combined preparative ultracentrifuge method (PUM) and dynamic light scattering (DLS) method to quantitatively characterized SWCNT particle size in dispersions under various sonication conditions; 2) designing combined ultrasonication and microfluidization processing protocol for high throughput and large-scale production of high quality SWCNT dispersions; 3) fabricating varied SWCNT thin film piezoresistive sensors through spray coating technique and immersion-drying post-treatment; and 4) investigating the effect of microstructures of SWCNTs on piezoresistivity of SWCNT thin film sensors. This experimental methodology for quantitative and systematic investigation of the processing-structure-property relationships provides a means for the performance optimization of CNT ensemble based piezoresistive sensors. As a start to understand the piezoresistive mechanism, the second focus of my Ph.D. research is studying charge transport behaviors in SWCNT thin films. It was found that the temperature-dependent sheet resistance of SWCNT thin films could be explained by a 3D variable range hopping (3D-VRH) model. More importantly, a strong correlation between the length of SWCNTs and the VRH parameter T0, indicating the degree of disorder of the electronic system, has been identified. With the structure dependent transport mechanism study, a very interesting topic - how T0 changes when SWCNT thin film is under a mechanical deformation, would be helpful for better understanding the piezoresistive mechanism of SWCNT thin film sensors. As demonstrated in transport mechanism study, SWCNT thin film exhibits a negative temperature coefficient (NTC) of resistance. In contrast, another family of carbon nanomaterials, graphite nanoplatelets (GNPs), shows positive temperature coefficient (PTC) of resistance, attributed to their metallic nature. Therefore, upon a wise selection of mass ratio of SWCNTs to GNPs for fabrication of hybrid SWCNT/GNP thin film piezoresistive sensors, a near zero temperature coefficients of resistance in a broad temperature range has been achieved. This unique self-temperature compensation feature along with the high sensitivity of SWCNT/GNP hybrid sensors provides them a vantage for readily and accurately measuring the strain/stress levels in different conditions. With the unique features of SWCNT/GNP hybrid thin film sensors, my future work will focus on application exploration on SWCNT/GNP thin film sensor based devices. For example, we have demonstrated that it is potential for man-machine interaction and body monitoring when coating the hybrid sensor on highly stretchable nitrile glove. The structure health monitoring (SHM) of composite materials could also be realized by coating the thin film sensor on a glass fiber surface and then embedding the fiber sensor in composite structure.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7478
Format: Thesis

Title: Supercritical Fluid Deposition of Vanadium Pentoxide within Carbon Nanotube Buckypaper for Electrochemical Capacitor.
Creator: Do, Quyet Huu, Zeng, Changchun, Zhang, Chuck, Zheng, Jim P., Zhang, Mei, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: There is a pressing need from a broad range of industries for high-performance energy storage devices with high power, high energy capacity, light weight, long lifetime, high efficiency, and low cost. A typical energy storage device, current electrochemical capacitors do not possess sufficient energy density to meet the needs. Recently utilization of oxide materials as pseudocapacitance materials has attracted a great deal of interest. However obtaining a high pseudocapacitance using an...
Show moreThere is a pressing need from a broad range of industries for high-performance energy storage devices with high power, high energy capacity, light weight, long lifetime, high efficiency, and low cost. A typical energy storage device, current electrochemical capacitors do not possess sufficient energy density to meet the needs. Recently utilization of oxide materials as pseudocapacitance materials has attracted a great deal of interest. However obtaining a high pseudocapacitance using an affordable oxide, while maintaining the high rate performance, remains elusive. This dissertation work aims to develop high-performance carbon nanotube (CNT) vanadium oxide hybrid nanostructured electrode materials for electrochemical capacitors. The CNT was in a form of freestanding thin film buckypaper (BP), which served as the current collector whilst providing double-layer capacitance, and vanadium oxide, coated on the CNT, was the pseudocapacitance material. Using a novel supercritical fluid deposition process, ultrathin vanadium oxide were uniformly deposited throughout the buckypaper with exceptional conformity at relatively low temperature, enabled by the unique properties of the supercritical fluids such as high solvation power, high diffusivity and zero surface tension. This overcame many of the transport limitations associated with the vanadium oxide material and indeed excellent electrode performance, particularly high rate performance, was achieved. The deposition process, the morphology and structure, and the capacitance behaviors of the composites were studied in detail, and the processing-morphology-electrochemical properties of the composites were elucidated. A high-pressure deposition system was constructed first for this dissertation research. Thereafter several deposition processes were investigated: physical adsorption - annealing, and in-situ reactive deposition. In the physical adsorption approach, the V2O5-buckypaper composite electrodes were fabricated by firstly physical adsorption of vanadium precursor in supercritical carbon dioxide (scCO2), followed by oxidation in air under elevated temperature. This approach resulted in the conformal deposition of V2O5 of molecular thickness onto the CNT and uniformly distributed throughout the BP. The V2O5 specificpseudo-capacitance of more than 1000 F/g were realized, even at high working power. To improve the active materials loading in the composite electrodes, two strategies were explored. In the first strategy, based on the qualitative fundamental understanding of the adsorption process, important physical parameters were identified, and the adsorption process was optimized by synergic use of physical understanding and statistical experiment design methods. The study resulted in an estimated second order model, which facilitated the search for adsorption conditions for higher precursor loading and higher total capacitance. The second strategy aimed to increase the available surface area for adsorption by the use of high specific surface area substrate material. Thus binder-free single-walled carbon nanotube (SWCNT)-activated carbon (AC) composite substrate was studied in comparison with the traditional activated carbon electrode. Based on thermogravimetric investigation of the precursor oxidation behavior, a conversion process was designed to maximize oxide materials conversion whilst minimizing substrate perturbation and degradation. The loading in the SWCNT-AC was increased by several times, and the composite electrodes showed excellent capacitance. In-situ reactive deposition was explored to further increase the oxide materials loading whiling maintaining the conformity and uniformity. Oxygen was used as the oxidizer and oxidation took place within the reactor. Conformal thin film of V2O5 layer with thickness varying from a few atomic layers to a few nm, with weight loading ~60%, was achieved. Together with the high V2O5 loading and high specific pseudo-capacitance enabled by the ultrathin film structure, excellent high-rate total capacitance was achieved. For example, the composite electrode with a 40% V2O5 showed a total capacitance ~130 F/g at a scan rate of 100 mV/s.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-8678
Format: Thesis

Title: Statistics-Enhanced Multistage Process Models for Integrated Design and Manufacturing of Poly (Vinyl Alcohol) Treated Buckeypaper.
Creator: Wang, Kan, Zhang, Chuck, Wu, Wei, Wang, Ben, Liang, Richard, Vanli, O. Arda, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Carbon nanotube (CNT) is considered a promising engineering material because of its exceptional mechanical, electrical, and thermal properties. Buckypaper (BP), a thin sheet of assembled CNTs, is an effective way to handle CNTs in macro scale. Pristine BP is a fragile material which is held together by weak van der Waals attractions among CNTs. This dissertation introduces a modified filtration based manufacturing process which uses poly (vinyl alcohol) (PVA) to treat BP. This treatment...
Show moreCarbon nanotube (CNT) is considered a promising engineering material because of its exceptional mechanical, electrical, and thermal properties. Buckypaper (BP), a thin sheet of assembled CNTs, is an effective way to handle CNTs in macro scale. Pristine BP is a fragile material which is held together by weak van der Waals attractions among CNTs. This dissertation introduces a modified filtration based manufacturing process which uses poly (vinyl alcohol) (PVA) to treat BP. This treatment greatly improves the handleability of BP, reduces the spoilage during transferring, and shortens the production time. The multistage manufacturing process of PVA-treated BP is discussed in this dissertation, and process models are developed to predict the nanostructure of final products from the process parameters. Based on the nanostructure, a finite element based physical model for prediction of Young's modulus is also developed. This accuracy of this physical model is further improved by statistical methods. The aim of this study is to investigate and improve the scalability of the manufacturing process of PVA-treated BP. To achieve this goal, various statistical tools are employed. The unique issues in nanomanufacturing also motivate the development of new statistical tools and modification of existing tools. Those issues include the uncertainties in nanostructure characterization due to the scale, limited number experimental data due to high cost of raw materials, large variation in final product due to the random nature in structure, and the high complexity in physical models due to the small scale of structural building blocks. This dissertation addresses those issues by combining engineering field knowledge and statistical methods. The resulting statistics-enhanced physical model provides an approach to design the manufacturing process of PVA-treated BP for a targeting property and tailor the robustness of the final product by manipulating the process parameters. In addition, since the methodology of this study deals with the common issues in general nanomanufacturing processes, this work also serves as a case study of a potential framework of process modeling procedure for similar nanomanufacturing processes. Several related topics are also investigated in this dissertation work. Those topics include a possible way to monitor the CNT dispersion process by observing the change in vibration structures using time series models, and an alternative method to handle the discrepancy between computer simulation and experimental data. Those topics, although not indispensable to the final goal, provide new angles to view the problem and a better understanding of the nanomanufacturing process. Some possible extensions of future studies are discussed at the end of this dissertation, including an improvement of manufacturing process, a possible application of PVA-treated BP, and a further application of the prediction model. Those topics represent a broader impact of this work. Subsequent studies of this dissertation, both the manufacturing aspect and the application aspect, are meaningful and worthwhile. Only with continuous advances in every field of BP research can a full realization of the potential of CNTs be achieved.
Show less
Date Issued: 2013
Identifier: FSU_migr_etd-7646
Format: Thesis

Title: On the Use of a Novel Recuperative Nanofluid Heat Transfer Methodology for Improving Photovoltaic Output Power in Residential and Industrial Applications.
Creator: Anthony, Thomas P., Pignatiello, Joseph J., Vanli, Arda, Roberts, Rodney, Zhang, Mei, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: ABSTRACT Since there has been an increase in the price of petroleum, there has been an increased need for photovoltaic systems over the last two decades. An increased number of private citizens are attracted to photovoltaic (PV) power as a viable source of independent renewable energy. Presently there is a mandate to continually improve the performance of the PV panels to maintain sustainability and to develop next generation PV systems. Most PV manufacturers state specifications of PV panels...
Show moreABSTRACT Since there has been an increase in the price of petroleum, there has been an increased need for photovoltaic systems over the last two decades. An increased number of private citizens are attracted to photovoltaic (PV) power as a viable source of independent renewable energy. Presently there is a mandate to continually improve the performance of the PV panels to maintain sustainability and to develop next generation PV systems. Most PV manufacturers state specifications of PV panels in terms of standard testing condition (STC) of 25º C or 77º F. However, many panels are operated in environments where temperatures are well above the level of STC reaching as high as 180º F (76º C). This has been shown to reduce the solar panel energy conversion, particularly the power output of the panels. To date literature has shown that the use of two cooling methods, water and ambient air to remove heat from the panels has proven minimally effective. This research proposes a method of heat reduction employing a recuperative nanofluid heat transfer system. The system employs a labyrinth of nanofluid filled tubes along the back of the PV panel. Through a field experiment, four combinations of a copper nanofluid combinations acting as a heat transfer medium were employed to remove the excess heat incident on four experimental units. The removal of heat from the solar panels to reservoirs simulating a domestic or industrial water heater simultaneously reduced the temperature of the panel to promote increased power output as well as water heating. The analysis of the data showed an average increase in reservoir temperature of 25º F. An analysis showed that the proposed system is more economical than either standard PV systems or the use of municipal utilities. The hope is that the proposed system will reduce the average citizen's energy cost by at least 30 percent as well as enable private citizens and some industries to operate independent of the utility grid.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-4695
Format: Thesis

Title: 2-D Reinforcement Structure for Fracture Strength and Fracture Toughness Enhancement for Alumina.
Creator: Ighodaro, Osayande Lord-Rufus, Okoli, Okenwa, Peterson-Hruda, Simone, Zhang, Mei, Liang, Zhiyong Richard, Department of Industrial and Manufacturing Engineering, Florida State...
Show moreIghodaro, Osayande Lord-Rufus, Okoli, Okenwa, Peterson-Hruda, Simone, Zhang, Mei, Liang, Zhiyong Richard, Department of Industrial and Manufacturing Engineering, Florida State University
Show less
Abstract/Description: Despite the attractive properties of advanced ceramics, they are not popular for structural applications even though they possess high strength. Their low fracture toughness and brittle fracture mode are unwelcome for high integrity structure. Moreover, they fail at loads far below their theoretical strengths due to their inherent flaws. These have led to the development of reinforcing strategies to help enhance the fracture resistance of ceramics. However, reported strengths value are still...
Show moreDespite the attractive properties of advanced ceramics, they are not popular for structural applications even though they possess high strength. Their low fracture toughness and brittle fracture mode are unwelcome for high integrity structure. Moreover, they fail at loads far below their theoretical strengths due to their inherent flaws. These have led to the development of reinforcing strategies to help enhance the fracture resistance of ceramics. However, reported strengths value are still far below theoretical strength, most reinforced ceramics suffer trade-off between strength and toughness, and most present reinforcement methods are material specific. In this work, a generic method for reinforcing ceramic materials for the enhancement of fracture resistance is described. Continuous ductile ligaments oriented in two orthogonal directions and forming 2-D network grid reinforcement structure was employed. The method involves two major stages: fabrication of regular channels in 2-D in ceramic matrix to form the preform and infiltration of the preform with the required reinforcement. Two different materials: carbon fibers and soft metal alloys were used as sacrificial materials for fabricating the aligned 2-D regular channels in alumina matrix. After the porous preforms were formed, molten aluminum alloys were infiltrated into the channels by the application of mechanical pressure, and this completes the composite fabrication process. Mechanical tests show that some porous preforms having area fraction of 2.7 % exhibited 27 % higher flexural strength than the solid specimens despite the porosity contained and this has been attributed to the ability of the channels to reduce the population and distribution of cracks in the porous material. The reinforced composites were also subjected to mechanical tests which revealed 217.6 % enhancement in flexural strength for the 7.79 % Al 7075 alloy reinforced composite. This magnitude of property enhancement was achieved due to the confinement of the matrix in the loop of the reinforcement and the beneficial residual compressive stress generated as a result of the difference in coefficient of thermal expansion (CTE) of the alumina and aluminum. The residual compressive stress delays crack initiation and crack propagation in the alumina matrix. It also reduces the stress concentration factor in the matrix, leading to higher failure stress and higher fracture toughness.
Show less
Date Issued: 2012
Identifier: FSU_migr_etd-5716
Format: Thesis

Theses and Dissertations (129)	+ -
Undergraduate Honors Theses (3)	+ -

Industrial engineering (95)	+ -
Engineering (28)	+ -
Manufacturing processes (27)	+ -
Production engineering (26)	+ -
Operations research (23)	+ -

Systems engineering (22)	+ -
Materials science (13)	+ -
Nanotechnology (5)	+ -
Materials (3)	+ -
Mechanical engineering (3)	+ -
Statistics (3)	+ -
Applied mathematics (2)	+ -
Nanoscience (2)	+ -
Aerospace engineering (1)	+ -
Artificial intelligence (1)	+ -
Chemistry (1)	+ -
Civil engineering (1)	+ -
Computer science (1)	+ -
Electrical engineering (1)	+ -
Medical ethics (1)	+ -
Planning (1)	+ -
Plastics (1)	+ -
Polymers (1)	+ -
Textile research (1)	+ -
Transportation (1)	+ -

text (132)	+ -
doctoral thesis (14)	+ -
master thesis (4)	+ -

Florida State University (129)	+ -
Liang, Zhiyong (42)	+ -
Zhang, Chuck (40)	+ -
Wang, Ben (38)	+ -
Okoli, Okenwa (35)	+ -

Search In

Pages

Pages

Sort Results By:

Narrow results by:

Collection

Topical Subject

Genre

Type of Resource

Language

Creator

Owner