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Title: Model Characteristics and Properties of Nanorobots in the Bloodstream.
Creator: Zimmer, Michael Makoto, Owusu, Yaw A., Roberts, Rodney G., Parker, Reginald, Zhang, Chun, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Many researchers have various visions and concepts about what the nanorobot will be like and what they will do. Most people see nanorobots doing a lot of functions in the medical field, having ideas of them doing cell repair, seek-and-destroy harmful diseases, clean arteries of cholesterol buildup, and much more. There are many questions that need to be answered as to what exactly is needed for the nanorobot to perform these medical functions. This project is not interested in the design of...
Show moreMany researchers have various visions and concepts about what the nanorobot will be like and what they will do. Most people see nanorobots doing a lot of functions in the medical field, having ideas of them doing cell repair, seek-and-destroy harmful diseases, clean arteries of cholesterol buildup, and much more. There are many questions that need to be answered as to what exactly is needed for the nanorobot to perform these medical functions. This project is not interested in the design of the nanorobot, but focuses on the characteristics and parameters that should be considered for a nanorobot to function through the bloodstream of a human body, specifically. To do this, a mobile robot was being used to traverse through a scaled model of the bloodstream. The scale model consisted of clear tubing or piping enclosed in a loop filled with liquid to nearly the exact viscosity of blood. The liquid had particles to emulate the various obstacles that a nanorobot would encounter like red blood cells and other molecules. The simulation had a continuous flow at the appropriate rate and pressure expected in the bloodstream. The pipe size was calculated setting the ratio of the diameter of a particular blood vessel over the diameter face of the assumed size of a nanorobot (DBV / DNR) equaling the diameter of the pipe (unknown variable) to the diameter face of the mobile robot (DPipe / Dsub). The pipe size came to be 6.66 inches, however pipe sizes come in increments of 2 inches larger than 4 inch pipes. It was settled to use 6 inch pipes. With this variable, the Reynolds number is the diameter of pipe times the velocity of the fluid over the kinematic viscosity of the fluid (R = (DPipe * ν) / υ). Setting the Reynolds value of the bloodstream equal to the Reynolds value of the model, the velocity of the pipe could be isolated. With that the flow rate was evaluated by multiplying the velocity to the cross-sectional area of the pipe (Flow Rate was equal to 0.2021392 gallon/minute). With all conditions met for an accurate model of the bloodstream, the physical model was designed and constructed then testing with the mobile robot was done to determine how the robot functions in the simulated environment. The results of the experiment showed that the mobile robot is influenced by the environment. The speed it travels decreases as viscosity of the fluid increases. The particles in the fluid also affect the speed along with the flow of the fluid. Mobility and control of the mobile robot were hindered with the increase of viscosity and the presence of particles. When traveling against the flow of the fluid it was further hindered. Stability of the craft increased along with viscosity but was chaotic traveling with particles. The performance of the mobile robot was affected by the conditions and parameters involved in the bloodstream.
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Date Issued: 2005
Identifier: FSU_migr_etd-0496
Format: Thesis

Title: Investigation of Vartm Processing of High Temperature RP-46 Resin System.
Creator: Prasad, Thammiah M., Zhang, Chuck, Okoli, Okenwa, Liang, Zhiyong, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: The advantages of using polymer matrix composites in various applications are very well known throughout many industries. Their introduction and subsequent development since the 1940's has led to major cost savings due to their lightweight and excellent mechanical properties. Off late, product designers have been taking advantage of improved thermal properties (CTE, thermo-oxidative stability) that these composite materials have to offer. This began with the development of PMR-15, a high...
Show moreThe advantages of using polymer matrix composites in various applications are very well known throughout many industries. Their introduction and subsequent development since the 1940's has led to major cost savings due to their lightweight and excellent mechanical properties. Off late, product designers have been taking advantage of improved thermal properties (CTE, thermo-oxidative stability) that these composite materials have to offer. This began with the development of PMR-15, a high temperature polyimide resin back in the 1970's. The aerospace industry has increasingly turned towards high temperature polymer matrix composites (HTPMC) to replace other heavier materials in engine components thus improving the thrust to weight of the engine. But, PMR-15 has a major drawback related to high safety standards that are needed during processing. The implementation of these controls during processing resulted in huge costs to the industry. This led to the development of a new polyimide high temperature resin system called RP-46 at NASA Langley research center. RP-46 has excellent thermal and mechanical properties comparable to PMR-15 and is safer to handle due to the absence of the lethal MDA monomer, a carcinogen. This research investigates the issues related to processing of RP-46 resin system using the Vacuum Assisted Resin Transfer Molding (VARTM) process, a cost effective method for manufacturing composite materials. The entire process is setup keeping in consideration the requirement of high temperature environments for processing of RP-46. A number of initial trials helped understand the dynamics of the process and identify critical factors and key parameters. The various laminates that were made were tested for mechanical properties (ASTM D3039 - Tensile strength and modulus) and thermal properties (Dynamic Mechanical Analysis, Thermal Mechanical Analysis, Thermal Gravimetric Analysis) were performed and the results were compared with RP-46 samples made using autoclave processing. Although the VARTM laminates had issues related to void contents and the release of volatiles during the infusion stage of the process, the VARTM process was found to be feasible to make composites with RP-46.
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Date Issued: 2004
Identifier: FSU_migr_etd-0441
Format: Thesis

Title: Characterization of Nanotube Buckypaper Manufacturing Process.
Creator: Yeh, Cherng-Shii, Liang, Zhiyong, Simpson, James R., Wang, Ben, Zhang, Chuck, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: The discovery of single-walled nanotubes (SWNTs) gives an important boost to nanomaterial research. Since the nanotubes have exceptional mechanical, thermal, and electrical properties, they are considered very promising reinforcement materials for developing high performance nanocomposites. One of the effective methods for fabricating nanotube composites is to make nanotubes into buckypaper form (Nanotube Buckypaper). The nanotubes are pre-formed into buckypaper of well-dispersed tube network...
Show moreThe discovery of single-walled nanotubes (SWNTs) gives an important boost to nanomaterial research. Since the nanotubes have exceptional mechanical, thermal, and electrical properties, they are considered very promising reinforcement materials for developing high performance nanocomposites. One of the effective methods for fabricating nanotube composites is to make nanotubes into buckypaper form (Nanotube Buckypaper). The nanotubes are pre-formed into buckypaper of well-dispersed tube network, so as to control tube dispersion and loading as well as microstructures in the resulting composites. In this research, we characterized the quality of buckypaper with different fabricating parameter combinations, and performed statistical analysis on the quality of the produced buckypapers. A statistical model of the nanotube buckypaper process was developed to investigate the contribution of fabricating parameters, including suspension concentration, sonication level and time, filtration vacuum pressure, and surfactant types on nanotube bundle quality as measured by rope size and pore size. Statistical modeling is also used to estimate the variability associated with manufacturing, the image taken, and the measurement processes. The statistical analysis shows that all the selected factors are influential to the quality of buckypaper, and the interactions between these factors contribute more than the factors themselves. Overall, the selection of surfactant is crucial to the formation of a uniform tube rope network of nanotube buckypaper in both average performance and variability. The microscopy characterization of the nanotube buckypaper samples, designed experiment, and variance components analysis all provide strong evidence that Triton X-100 is the best surfactant in terms of better dispersion effect, higher repeatability and less variability in producing nanotube buckypapers. Therefore, the process of fabricating buckypaper with Triton X-100 is suggested to construct a reliable and repeatable model of nanotube buckypaper process, and the model can be further used to optimize operating parameters and predict the quality of nanotube buckypapers.
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Date Issued: 2004
Identifier: FSU_migr_etd-0420
Format: Thesis

Title: Performance of Control Charts for Weibull Processes.
Creator: Zhang, Mang, Pignatiello, Joseph J., Awoniyi, Samuel A., Vanli, Arda, Okoli, Okenwa, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Statistical Process Control (SPC) is a statistical method for monitoring variability of processes. Process variation can be categorized as common cause and special cause. Common causes are the natural or expected variation of some change in the process. The presence of a special cause indicates that the process is not in a state of statistical control. The SPC methodology dictates that a search should be initiated when a special cause is detected. This thesis is about the set-up of magnitude...
Show moreStatistical Process Control (SPC) is a statistical method for monitoring variability of processes. Process variation can be categorized as common cause and special cause. Common causes are the natural or expected variation of some change in the process. The presence of a special cause indicates that the process is not in a state of statistical control. The SPC methodology dictates that a search should be initiated when a special cause is detected. This thesis is about the set-up of magnitude robust control chart and CUSUM charts for detecting changes in Weibull processes. The research includes the comparison of the ARL performance of the control charts.
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Date Issued: 2009
Identifier: FSU_migr_etd-0537
Format: Thesis

Title: Dimension Variation Prediction and Control for Composites.
Creator: Dong, Chensong, Zhang, Chuck, Buzyna, George, Liang, Zhiyong, Okoli, Okenwa, Wang, Ben, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: This dissertation presents a systematic study on the dimension variation prediction and control for polymer matrix fiber reinforced composites. A dimension variation model was developed for process simulation based on thermal stress analysis and finite element analysis (FEA). This model was validated against the experimental data, the analytical solutions and the data from literature. Using the FEA-based dimension variation model, the deformations of typical composite structures were studied...
Show moreThis dissertation presents a systematic study on the dimension variation prediction and control for polymer matrix fiber reinforced composites. A dimension variation model was developed for process simulation based on thermal stress analysis and finite element analysis (FEA). This model was validated against the experimental data, the analytical solutions and the data from literature. Using the FEA-based dimension variation model, the deformations of typical composite structures were studied and the regression-based dimension variation model was developed. The regression-based dimension variation model can significantly reduce computation time and provide a quick design guide for composite products with reduced dimension variations. By introducing the material modification coefficient, this comprehensive model can handle various fiber/resin types and stacking sequences. It eliminates the complicated, time-consuming finite element meshing and material parameter defining process. The deformation compensation through tooling design was investigated using the FEA-based and the regression-based dimension variation models. The structural tree method (STM) was developed to compute the assembly deformation from the deformations of individual components, as well as the deformation of general shape composite components. The STM enables rapid dimension variation analysis/synthesis for complex composite assemblies with the regression-based dimension variation model. Using the STM and the regression-based dimension variation model, design optimization and tolerance analysis/synthesis were conducted. The exploring work presented in this research provides a foundation to develop practical and proactive dimension control techniques for composite products.
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Date Issued: 2003
Identifier: FSU_migr_etd-0711
Format: Thesis

Title: Wavelet Methods in Quality Engineering: Statistical Process Monitoring and Experimentation for Profile Responses.
Creator: Zeisset, Michelle S., Pignatiello, Joseph J., Simpson, James R., Chicken, Eric, Robinson, Timothy J., Department of Industrial and Manufacturing Engineering, Florida State...
Show moreZeisset, Michelle S., Pignatiello, Joseph J., Simpson, James R., Chicken, Eric, Robinson, Timothy J., Department of Industrial and Manufacturing Engineering, Florida State University
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Abstract/Description: Advances in measurement technology have led to an interest in methods for analyzing functional response data, also known as profiles. Profiles are response variables that, rather than taking on a single value, can be considered a function of one or more independent variables. In quality engineering, profiles present challenges for both statistical process monitoring and experimentation because they tend to be high dimensional. High dimensional responses can result in low power tests...
Show moreAdvances in measurement technology have led to an interest in methods for analyzing functional response data, also known as profiles. Profiles are response variables that, rather than taking on a single value, can be considered a function of one or more independent variables. In quality engineering, profiles present challenges for both statistical process monitoring and experimentation because they tend to be high dimensional. High dimensional responses can result in low power tests statistics and may preclude the use of conventional multivariate statistics. Moreover, profile responses can differ at any combination of locations along the independent variable axes, compared to a simple increase or decrease for a single-valued response. This leads to potentially ambiguous interpretation of results and may induce a disparity in the ability to detect differences that occur at only a few points (a local difference) compared to a systematic difference that impacts the entire length of the profile (a global difference). Wavelet-based methods show a strong potential for addressing these challenges. This dissertation presents an overview of wavelets, emphasizing the potential advantages of wavelets for statistical process monitoring applications. Next, the performances of wavelet-based, parametric, and residual control chart methods to quickly detect a range of local and global within-profile change types are compared and contrasted. Finally, four methods are proposed for testing hypotheses about profile differences between treatments. The performance of these methods are compared and an extension to one-way ANOVA is introduced. We conclude that for both profile monitoring and hypothesis testing applications, wavelet-based methods can out-perform other approaches. In addition, wavelet-based statistical methods tend be more robust than competing approaches when the local or global nature of process changes or profile differences are not known a priori.
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Date Issued: 2008
Identifier: FSU_migr_etd-0586
Format: Thesis

Title: Assessment of Triboluminescent Materials for In-Situ Health Monitoring.
Creator: Dickens, Tarik Jamel, Okoli, Okenwa, Liang, Zhiyong, Simpson, James, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Advanced composites which offer robust mechanical properties are being increasingly used for structural applications in the aerospace, marine, defense and transportation industries. However, the anisotropic nature of composite materials leaves it susceptible to problematic failure; the development of means for detecting failure is imperative. As design and functionality requirements of engineering structures such as spacecraft, aircraft, naval vessels, buildings, dams, bridges and ground...
Show moreAdvanced composites which offer robust mechanical properties are being increasingly used for structural applications in the aerospace, marine, defense and transportation industries. However, the anisotropic nature of composite materials leaves it susceptible to problematic failure; the development of means for detecting failure is imperative. As design and functionality requirements of engineering structures such as spacecraft, aircraft, naval vessels, buildings, dams, bridges and ground-based vehicles become more complex; structural health monitoring (SHM) and damage assessment is becoming more rigorous. Though structures involved have regular costly inspections, the damage associated with composites in SHM systems can lead to catastrophic and expensive failures. Industry and research have no single technique used on its own to provide reliable results. Integrating several nondestructive evaluation (NDE) techniques could provide a solution for real-time health monitoring. Such studies, utilizing acoustic emission (AE), A-scans, C-scans, and laser shearography have reported considerable success. Nevertheless, damage detection has to be reliable and cost effective. The answer may lie with the development of SHM systems by the use of triboluminescent crystals, as well as optical fibers embedded in the composite matrix. These crystals react to straining or fracture by emitting light of varied luminous intensity. Thus, a fiber-reinforced plastic (FRP) laminate doped with Triboluminescent (TL) or Mechanoluminescent (ML) crystals, acting as health sensors to its host material, will give an indication of crack initiation well ahead of catastrophic failure(s). The development of an in-situ health monitoring system for safety critical structures is a viable route through 'Triboluminescence'. Assessing the viability of a proposed structural sensor system requires cross-linking between key areas in science and engineering. Initial testing has shown that light can propagate through doped resins alone, as well as doped FRP laminates. The luminous intensities relation to impact velocity adds credence to a monitoring system that can characterize impact activity. However, Triboluminescent crystals have high material density. In response, a two-dimensional rotational mold was built to counteract massive settling under normal vacuum molding processes. Micro-structural evaluations using scanning electron microscopy (SEM) and EDAX imaging have aided in demystifying particulate dispersion of TL fillers through use of image processing.
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Date Issued: 2007
Identifier: FSU_migr_etd-0734
Format: Thesis

Title: Comparative Analysis of the Power Output of Crystalline Photovoltaic (PV) Modules Using Solar Tracking System.
Creator: Anthony, Thomas P., Owusu, Yaw A., Simpson, James, Moore, Carl A., Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: The focus of this thesis was to employ the use of two widely used types of photovoltaic (PV) modules namely monocrystalline and polycrystalline in a tracking system to determine which produces the greater output and compare these results to those reached by my predecessor, Michael O. Case[Case, 2003]. Several factors affect the overall productivity of a solar system. These include but are not limited to, time of day, time of year, latitude and atmospheric conditions, all of which were dealt...
Show moreThe focus of this thesis was to employ the use of two widely used types of photovoltaic (PV) modules namely monocrystalline and polycrystalline in a tracking system to determine which produces the greater output and compare these results to those reached by my predecessor, Michael O. Case[Case, 2003]. Several factors affect the overall productivity of a solar system. These include but are not limited to, time of day, time of year, latitude and atmospheric conditions, all of which were dealt with throughout this thesis. The thesis began with the design and assembly of a solar tracking system. This system was used to collect data using monocrystalline and polycrystalline modules in various configurations. The configurations were stationary zero degrees, stationary forty degrees and solar tracking at forty degrees. Once data was acquired, it was entered in to the statistical software "Design Expert V6.0". Statistical analysis was then performed to determine the effect the chosen factors had on the power output of the two types of modules in terms of which type provides greater output and in what configuration. It was determined that the monocrystalline module produces greater power output than its polycrystalline counterpart. A final experiment was set up to determine the mode that produces the greatest power output. The results from the experiment revealed that monocrystalline modules deliver greater power in a tracking configuration. However, it may be necessary to consider the effects of temperature depending on application of these modules.
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Date Issued: 2006
Identifier: FSU_migr_etd-0222
Format: Thesis

Title: Application of Experimental Design for Efficient Wind Tunnel Testing: The Tandem Wing Mav Case.
Creator: English, Teresa Gail, Simpson, James R., Landman, Drew, Okoli, Okenwa I., Pignatiello, Joseph J., Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Micro air vehicles (MAVs) are small scale unmanned aerial vehicles (UAVs) that are used for reconnaissance, intelligence gathering and battle damage assessment. The U.S. Air Force Research Lab Munitions Directorate develops MAVs for various defense missions. The case involves a tandem wing MAV that is designed to have retractable wings for transport, control surfaces on the aft wing, and two different vertical tail configurations. Wind tunnel testing is one of the vital steps in MAV...
Show moreMicro air vehicles (MAVs) are small scale unmanned aerial vehicles (UAVs) that are used for reconnaissance, intelligence gathering and battle damage assessment. The U.S. Air Force Research Lab Munitions Directorate develops MAVs for various defense missions. The case involves a tandem wing MAV that is designed to have retractable wings for transport, control surfaces on the aft wing, and two different vertical tail configurations. Wind tunnel testing is one of the vital steps in MAV development for evaluating and ensuring that stability and control requirements are met for sustained flight. Traditionally, wind tunnel tests have been performed using a one factor at a time (OFAT) approach. Wind tunnel OFAT involves testing at many levels of one particular factor, usually angle of attack (AoA), while holding all other input factors constant; this technique is then repeated for various input factor configurations. This classic approach can be useful in determining the effect that each input alone has on the desired response. However, OFAT is not capable of identifying the influence that inputs interacting with one another have on the response, which commonly affect aircraft performance. Furthermore, OFAT is not capable of characterizing uncertainty that is present in experimentation. The research objective is to develop a testing strategy that provides an efficient number of test points to run in the wind tunnel effectively characterizing the aerodynamic behavior of MAVs as a function of design changes, changes in attitude and control inputs, while reducing costs and resources using design of experiments (DOE) and response surface methods (RSM). The research involves one of the first applications of second-order split plot designs, as well as the traditional completely randomized design. The DOE/RSM approach will be directly compared to the traditional OFAT wind tunnel testing that is performed during the same test period. The analyses resulting from the DOE/RSM approach will highlight its capabilities in identifying factor interactions, characterizing system uncertainty, and providing stability and control analyses – the common objectives of wind tunnel testing. The outcome of the study will demonstrate the effectiveness of DOE/RSM techniques when tailored to meet the specifications of wind tunnel testing. Some characteristics involved with the wind tunnel environment are low noise, qualitative factors, hard-to-change factors, and second-order models. The collaboration of experimental design techniques adapted to traditional wind tunnel testing techniques will provide a powerful approach to characterizing and optimizing aerodynamic systems.
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Date Issued: 2007
Identifier: FSU_migr_etd-0559
Format: Thesis

Title: Fault Diagnosis in Multivariate Manufacturing Processes.
Creator: Ding, Yi, Vanli, Arda, Wang, Ben, Zhang, Chuck, Pignatiello, Joseph J., Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: As manufacturing systems are becoming more complex, the use of multivariate fault detection and diagnosis methods are increasingly important. Effective fault detection and diagnosis methods can minimize cost of rework, plant down time and maintenance time and improve reliability and safety. This thesis proposes Principal Components Analysis (PCA) based root cause identification approach for quality improvement in complex manufacturing processes. Simulation studies are presented to demonstrate...
Show moreAs manufacturing systems are becoming more complex, the use of multivariate fault detection and diagnosis methods are increasingly important. Effective fault detection and diagnosis methods can minimize cost of rework, plant down time and maintenance time and improve reliability and safety. This thesis proposes Principal Components Analysis (PCA) based root cause identification approach for quality improvement in complex manufacturing processes. Simulation studies are presented to demonstrate the improved diagnosability of the proposed approach compared to existing methods.
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Date Issued: 2010
Identifier: FSU_migr_etd-0729
Format: Thesis

Title: Optimization of Ultraviolet Lamp Placement for the Curing of Composite Manufactured by the Ridft Process.
Creator: Adewuyi, Olalekan Sunday, Okoli, Okenwa I., Awoniyi, Samuel A., Jack, David A., Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: The ultraviolet curing technique, when applied to composite manufacturing processes, allows UV rays to radiate the component reducing the curing time of composite materials from hours to minutes. This technique has been demonstrated with the Resin Infusion between Double Flexible Tooling (RIDFT) process for flat components. However, the curing of composites other than flat components remains a challenge. Applying UV curing to three-dimensional geometries mostly requires utilization of several...
Show moreThe ultraviolet curing technique, when applied to composite manufacturing processes, allows UV rays to radiate the component reducing the curing time of composite materials from hours to minutes. This technique has been demonstrated with the Resin Infusion between Double Flexible Tooling (RIDFT) process for flat components. However, the curing of composites other than flat components remains a challenge. Applying UV curing to three-dimensional geometries mostly requires utilization of several lamps positioned around the component. Not only is this expensive, but it may allow for UV exposure overlap resulting in excessive curing of some areas on the component. Trial-and-error positioning, utilization of large arrays of UV lamps with components moving on a conveyor, and robotically actuated UV lamps have been employed in some quarters. These methods are too expensive, time consuming, and complex, thus negating the idea of simplicity that composite manufacturing processes tend to portray. To tackle this problem, a general-purpose model was proposed. Solving this model involves two stages: numerical integration using Gauss quadrature method, and optimization problem using Davidon-Fletcher Powell (DFP) algorithm. The model predicts the UV lamps' optimum positions and generates the UV intensity on the predefined sections on the composite substrates. Furthermore, three-dimensional composite materials were manufactured using different manufacturing parameters. Mechanical and rheological tests were carried out to determine uniformity of curing; the results of these tests were compared with three-dimensional catalytic cured composite components. The UV cured composites have mechanical properties that are comparable with the catalytic cured composite.
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Date Issued: 2009
Identifier: FSU_migr_etd-0120
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
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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.
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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.
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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
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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.
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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
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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.
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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
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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.
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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
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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%.
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Date Issued: 2015
Identifier: FSU_2015fall_Veliky_fsu_0071N_12979
Format: Thesis

Title: Continuous Buckypaper Manufacturing Process: Process Investigation and Improvement.
Creator: Young, Jasmine, Liang, Zhiyong, Wang, Ben, Zhang, Chuck, Vanli, Arda, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Carbon nanotubes have excellent electrical, thermal, and mechanical properties as determined theoretically and experimentally. Their properties make them great candidates for use in a number of applications ranging from lightning strike protection for airplanes to computer heat sink. However, carbon nanotubes are incredibly small, with diameters as small as 1nm and just a few micrometers long. The nanoscale size makes carbon nanotubes impractical to be used individually for many industrial...
Show moreCarbon nanotubes have excellent electrical, thermal, and mechanical properties as determined theoretically and experimentally. Their properties make them great candidates for use in a number of applications ranging from lightning strike protection for airplanes to computer heat sink. However, carbon nanotubes are incredibly small, with diameters as small as 1nm and just a few micrometers long. The nanoscale size makes carbon nanotubes impractical to be used individually for many industrial purposes, thus methods have been developed to fabricate macroscale networks of carbon nanotubes. The carbon nanotube networks, also called Buckypaper, have showed mechanical, thermal and electrical properties inferior to those of individual nanotubes. Extensive work has been conducted to develop and optimize suitable production methods of producing high quality Buckypaper and enhance their properties. Many approaches are capable of producing a carbon nanotube network, but most are not able to scale up for industrial applications due to size and production rate limitations. This research focuses on two aspects of Buckypaper manufacturing improvements. The first is to test 90 mm samples of Buckypaper disks to determine the impact of each processing parameter on the quality and properties. Statistic analysis was used to reveal the effect of processing parameters. Utilizing these results, a long sample of Buckypaper was produced and examined for property and quality consistency along the sample length, using modified customer-made continuous filter devices. Additionally, long samples with larger width were produced to demonstrate production rate of continuous Buckypaper manufacturing. Through this research it was found that the electrical conductivity of the Buckypaper was affected positively by an increase in sonication pressure. Additionally, increases in pressure and increase in power of sonication led to an increase of Buckypaper strength. Strength and electrical properties of the continuous Buckypaper were considered consistent throughout the length. These results provide essential understanding of the continuous Buckypaper manufacturing process.
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Date Issued: 2009
Identifier: FSU_migr_etd-0872
Format: Thesis

Title: Development of Carbon Nanotube/Carbon Fiber Multiscale Reinforcement Composites.
Creator: Davey, Kirk-Duval S., Liang, Richard, Okoli, Okenwa, Sands, James, Parker, Reginald, Wang, Ben, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: High performance composites are currently being used in the marine, automotive, aerospace and defense industries. These industries demand materials with properties that are similar or better than conventional metals at a fraction of the weight. The development of nanoparticle reinforced composites is presently one of the most explored areas in materials science and engineering. The exceptional properties of nanoparticles have made them a focus of widespread research. By combining...
Show moreHigh performance composites are currently being used in the marine, automotive, aerospace and defense industries. These industries demand materials with properties that are similar or better than conventional metals at a fraction of the weight. The development of nanoparticle reinforced composites is presently one of the most explored areas in materials science and engineering. The exceptional properties of nanoparticles have made them a focus of widespread research. By combining nanoparticles with traditional reinforcement materials, multiscale composites can be produced with superior properties to that of regular composites. This research focuses on the development of multiscale reinforcement composites, through the use of carbon nanotubes (CNTs), IM7 and T800 carbon fibers and SC-79 epoxy resin. Vacuum assisted resin transfer molding and hand lay-up/ vacuum bagging processes were evaluated for the manufacturing of multiscale composites. Results from this research showed that the use of carbon nanotubes can increase the tensile strength by up to 27% and toughness by up to 38%, with the addition of 2.5wt% multiwall carbon nanotubes (MWNTs). However there were no significant changes in the flexural properties with the addition of carbon nanotubes. Analysis of the fracture surfaces, using scanning electron microscopy showed that there was good dispersion of the carbon nanotubes through out the matrix material. The good dispersion of tubes aided in toughening the SC-79 epoxy resin. This toughening effect was evident though the change in crack propagation patterns on the fracture surface. There was also evidence of the nanotubes bridging cracks and holding resin particles together, which also lead to increased fracture toughness
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Date Issued: 2005
Identifier: FSU_migr_etd-0823
Format: Thesis

Title: Polypyrrole as a Smart Material for Phosphate Contaminate Detection in Water.
Creator: Woodard, Yoshino N., Owusu, Yaw A., Parker, Reginald, Kalu, Peter N., Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Polypyrrole is a conductive polymer that has the potential to be used in many systems where conductivity can be studied. Polypyrrole when combined with a catalyst such as calcium acetate maybe able to provide a method of detecting phosphate in water systems. The hypothesis of this research explores the concept that a polypyrrole sensor could be manufactured via a casting method to produce a sensor that detects phosphates in water. Varying three primary factors produced a designed experiment...
Show morePolypyrrole is a conductive polymer that has the potential to be used in many systems where conductivity can be studied. Polypyrrole when combined with a catalyst such as calcium acetate maybe able to provide a method of detecting phosphate in water systems. The hypothesis of this research explores the concept that a polypyrrole sensor could be manufactured via a casting method to produce a sensor that detects phosphates in water. Varying three primary factors produced a designed experiment and ANOVA analysis and comparison of means for three response variables: voltage, resistance and conductivity (calculated). Careful attention was paid to the values of the response variables across the geometry of the sensor prototypes. The sensor was evaluated for accuracy, sensitivity after multiple uses, and selectivity. After examining all of the data, the information obtained did not disprove the hypothesis, however it pointed to calcium acetate as the most powerful factor in the polypyrrole sensor in the accuracy test. Sensitivity and Selectivity tests had mixed findings. The samples not containing calcium acetate near the surface did not produce great changes in the response variables. The work presented in this thesis is an analysis of the raw data and materials used for generating the polypyrrole sensor prototype in order to introduce a new concept for manufacturing sensors using advanced materials; namely smart structures as sensors.
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Date Issued: 2006
Identifier: FSU_migr_etd-0787
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
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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.
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Date Issued: 2018
Identifier: 2018_Su_Hammel_fsu_0071E_14711
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.
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Date Issued: 2014
Identifier: FSU_migr_uhm-0361
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.
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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.
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Date Issued: 2015
Identifier: FSU_migr_uhm-0585
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
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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.
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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
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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.
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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
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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.
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Date Issued: 2018
Identifier: 2018_Sp_Baloglu_fsu_0071N_14559
Format: Thesis

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
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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.
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Date Issued: 2019
Identifier: 2019_Spring_Ren_fsu_0071E_15160
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
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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.
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Date Issued: 2018
Identifier: 2018_Fall_Shan_fsu_0071E_14859
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
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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.
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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
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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.
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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
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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.
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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
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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.
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Date Issued: 2019
Identifier: 2019_Summer_Nguyen_fsu_0071E_15140
Format: Thesis

Title: Carbon Nanotube Buckypaper Permeability and Prepreg Process Study.
Creator: Click, Bryant Marshall, Liang, Richard, Wang, Ben, Okoli, Okenwa, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Carbon nanotubes (CNTs) possess great potential for developing high-performance and multifunctional nanocomposites for a wide variety of applications. As the cost of producing CNT buckypaper, a thin film of CNT networks, continues to decrease while the quality increases, more users and companies are becoming interested in buckypaper for potential applications. Many of these applications, such as electromagnetic interference (EMI) shielding and fire retardant surface skins for fiber-reinforced...
Show moreCarbon nanotubes (CNTs) possess great potential for developing high-performance and multifunctional nanocomposites for a wide variety of applications. As the cost of producing CNT buckypaper, a thin film of CNT networks, continues to decrease while the quality increases, more users and companies are becoming interested in buckypaper for potential applications. Many of these applications, such as electromagnetic interference (EMI) shielding and fire retardant surface skins for fiber-reinforced composites or plastics, may not require buckypaper-based composites to be much stronger compared to fiber-reinforced composites. This means that there is a market for buckypaper even without its theoretical super strength, but desired functionality. There is however a number of challenges with the potential scale-up production of composite parts with affordable buckypaper materials usually made of low cost CNTs, such as multi-walled carbon nanotubes (MWNTs). Such buckypaper is usually very lightweight (10-25 g/m2), thin (10-20 microns), and fragile, hence even small variations and damage in the wet lay-up process can result in large quality variations in the final buckypaper composite. These variations include buckypaper volume fraction, resin rich areas, and contact between BP and other reinforcement materials etc. Thus, keeping the consistency of the resulting microstructure and quality of buckypaper composites is a very challenging issue. The objective of this project is to study nanostructure-permeability relationships of different types of buckypaper materials, and explore effective prepreg processes to make buckypaper composites with greatly increased consistency, quality, CNT weight fraction and uniformity in the resulting products. The experimental results show that buckypapers have very low permeability, about 8-12 orders lower than those of carbon fiber preform cases, and also sensitive to liquid polarity due to their nanoscale porosity and large surface area. Both solution and resin film transfer prepregging processes were studied to pre-impregnate buckypaper to achieve 50 wt. % CNT concentration. The late one showed better quality in the resultant nanocomposites, but difficult for high viscosity resins. Three case studies were also conducted to demonstrate quality and property consistency of buckypaper composites.
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Date Issued: 2010
Identifier: FSU_migr_etd-3581
Format: Thesis

Title: Preparation and Characterization of Magnetically Aligned Carbon Nanotube Buckypaper and Composite.
Creator: Shankar, Kadambala Ravi, Liang, Zhiyong, Wang, Ben, Zhang, Chuck, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Carbon nanotubes are theoretically one of the strongest and stiffest materials with a calculated tensile strength of ~200 giga Pascal and modulus of more than 1-4 tera Pascal for a single walled nanotube (SWNT). If the mechanical properties of SWNT could be effectively incorporated into a polymer matrix, composites with lightweight, exceptional strength and stiffness can be achieved. The effective utilization of nanotubes in composites for applications depends on the ability to disperse the...
Show moreCarbon nanotubes are theoretically one of the strongest and stiffest materials with a calculated tensile strength of ~200 giga Pascal and modulus of more than 1-4 tera Pascal for a single walled nanotube (SWNT). If the mechanical properties of SWNT could be effectively incorporated into a polymer matrix, composites with lightweight, exceptional strength and stiffness can be achieved. The effective utilization of nanotubes in composites for applications depends on the ability to disperse the nanotubes uniformly throughout the matrix. Carbon nanotubes are anisotropic in nature. Therefore to take advantage of the nanotubes in the axial direction, controlled tube orientation or degree of alignment of nanotubes in the polymer matrix is very important to realize their high mechanical and functional properties. The nanocomposites produced by current conventional methods using direct mixing, melt blending or solution casting have failed to yield significant improvements in composite modulus. Although tremendous progress has been made towards understanding the properties of individual carbon nanotubes, but attaining the true potential of the bulk polymeric nanocomposites have been hindered by the lack of uniform SWNT dispersion, poor interfacial bonding, inadequate tube loading and uncontrollable tube orientation or degree of alignment. This thesis work developed an innovative approach for producing nanocomposites that has uniform SWNT dispersion, high tube loading and most importantly controlled tube orientation. In this research, these properties in composites were achieved by using magnetically aligned buckypapers and resin infusion system. The aligned nanotube buckypaper and composite were characterized using AFM and SEM. The mechanical properties of these materials were experimentally determined using DMA and were theoretically verified. The electrical properties of these materials were also experimentally determined using 4-probe resistivity measurements. Significant tube alignment has been achieved in the resultant buckypaper and nanocomposites. It is shown that the developed method is an effective way for producing nanocomposites with uniform SWNT dispersion desired tube alignment and high tube loading.
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Date Issued: 2003
Identifier: FSU_migr_etd-3403
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.
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Date Issued: 2012
Identifier: FSU_migr_etd-4695
Format: Thesis

Title: Nanowire Alignment and Patterning via Evaporation-Induced Directed Assembly.
Creator: Abdelsalam, Farag, Zhang, Mei, Okoli, Okenwa, Liang, Zhiyong Richard, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: The post synthetic assembly of nanowires into desired configurations presents a unique challenge. The inherent size of nanowires does not lend it self to a method or process capable of easily arranging or manipulating these materials. The recent understanding of how contact-line deposition, or the "coffee-ring effect", influences isotropic particles has lead to interest in investigating its influence over nanowires. Research has shown that nanowires can be aligned and selectively deposited at...
Show moreThe post synthetic assembly of nanowires into desired configurations presents a unique challenge. The inherent size of nanowires does not lend it self to a method or process capable of easily arranging or manipulating these materials. The recent understanding of how contact-line deposition, or the "coffee-ring effect", influences isotropic particles has lead to interest in investigating its influence over nanowires. Research has shown that nanowires can be aligned and selectively deposited at the edge of a drying droplet as a result of evaporation-induced capillary flow. From this basic understanding several methods have developed with the intent of producing a facile, robust, and scalable nanowire assembly process. This work provides insight into the coffee-ring effect and the mechanisms that draw from it to align, assemble, and pattern nanowire structures prior to introducing and providing the results of a new contact line deposition method.
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Date Issued: 2011
Identifier: FSU_migr_etd-4679
Format: Thesis

Title: Design, Manufacture and Performance of Solar Powered Floating Fountaing.
Creator: Gomez, Eduardo J., Owusu, Yaw A., Roberts, Rodney, Simpson, James, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Photovoltaic (PV) systems behave in an extraordinary and useful way: they react to light by transforming part of the incoming photons into electricity. Since PV installations require no fuel to operate, produce no pollution while producing electricity, they require little maintenance and are modular. These unique properties make the technology a cost and energy-effective means of permitting a wide range of solar- electric applications. Thus, innovative design and manufacture of PV devices and...
Show morePhotovoltaic (PV) systems behave in an extraordinary and useful way: they react to light by transforming part of the incoming photons into electricity. Since PV installations require no fuel to operate, produce no pollution while producing electricity, they require little maintenance and are modular. These unique properties make the technology a cost and energy-effective means of permitting a wide range of solar- electric applications. Thus, innovative design and manufacture of PV devices and equipment, offers a new vision for consumers and business as to how power can be provided. One such application involves the design and manufacture of a Solar-Powered Floating Fountain, including a robust design of experiment, performance, cost and safety analyses, is presented in this thesis. The uniqueness of the fountain manufactured for this research is the capability for aeration of stagnant water bodies, such as lakes and ponds. Aeration of these water bodies by using solar power is not only a new application of the renewable energy, but also, it provides an affordable method to promote biodiversity in stagnant ponds and lakes. The fountain was built by the Research Center for Cutting-Edge Technologies (RECCET) and installed on a pond at Innovation Park, Tallahassee. The system is composed of two pumps, an air compressor, six solar panels, kit of batteries, a linear current booster, pressurized water tank and the float. Aeration was by exposing the water to air through the nozzles on the tank. By using this technique, the lake gained dissolved oxygen in the lowest layer, accomplishing the main objective of this project. Statistical analysis using a Split Plot design showed a significant uptake of both dissolved oxygen and destratification.
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Date Issued: 2006
Identifier: FSU_migr_etd-4152
Format: Thesis

Title: Study of a New Manufacturing Technology for Multi-Functional Composite Structures with Aerosol-Jet Printing.
Creator: Zhao, Da (Daniel), Wang, Ben, Zhang, Mei, Liu, Tao, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Traditional multifunctional composite structures are produced by embedding parasitic parts, such as foil sensors, optical fibers and bulky connectors. As a result, the mechanical properties of the composites, especially the interlaminar shear strength (ILSS), could be largely undermined. In the present study, we demonstrated an innovative aerosol-jet printing technology for printing electronics inside composite structures without degrading the mechanical properties. Using the maskless fine...
Show moreTraditional multifunctional composite structures are produced by embedding parasitic parts, such as foil sensors, optical fibers and bulky connectors. As a result, the mechanical properties of the composites, especially the interlaminar shear strength (ILSS), could be largely undermined. In the present study, we demonstrated an innovative aerosol-jet printing technology for printing electronics inside composite structures without degrading the mechanical properties. Using the maskless fine feature deposition (below 10µm) characteristics of this printing technology and a pre-cure protocol, strain sensors were successfully printed onto carbon fiber prepregs to enable fabricating composites with intrinsic sensing capabilities. The degree of pre-cure of the carbon fiber prepreg on which strain sensors were printed was demonstrated to be critical. Without pre-curing, the printed strain sensors were unable to remain intact due to the resin flow during curing. The resin flow-induced sensor deformation can be overcome by introducing 10% degree of cure of the prepreg. In this condition, the fabricated composites with printed strain sensors showed almost no mechanical degradation (short beam shearing ILSS) as compared to the control samples. Also, the failure modes examined by optical microscopy showed no difference. The resistance change of the printed strain sensors in the composite structures were measured under a cyclic loading and proved to be a reliable mean strain gauge factor of 2.2±0.06 which is comparable to commercial foiled metal strain gauge.
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Date Issued: 2011
Identifier: FSU_migr_etd-6092
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
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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.
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Date Issued: 2012
Identifier: FSU_migr_etd-5716
Format: Thesis

Title: Electrical Properties of Carbon Nanotube Networks: Characterization, Modeling and Sensor Applications.
Creator: Li, Shu, Liang, Richard, Andrei, Petru, Vanli, Arda, Zhang, Chuck, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Carbon nanotubes (CNTs) possess extraordinary electrical properties including conductivity that is comparable to metals and breakdown current density that is orders of magnitude higher than copper. In order to take advantage of the electrical performance of CNTs in engineering applications, macroscopic carbon nanotube networks (NTN) are fabricated by entangling large amounts of CNTs into thin sheets. However, the electrical properties of these networks are much lower than those of individual...
Show moreCarbon nanotubes (CNTs) possess extraordinary electrical properties including conductivity that is comparable to metals and breakdown current density that is orders of magnitude higher than copper. In order to take advantage of the electrical performance of CNTs in engineering applications, macroscopic carbon nanotube networks (NTN) are fabricated by entangling large amounts of CNTs into thin sheets. However, the electrical properties of these networks are much lower than those of individual nanotubes. Stretch-induced alignment of CNTs is an effective approach to enhance the electrical conductivity of the NTNs. However, the alignment mechanism of NTNs during the stretching process has not been fully investigated. This study employed in-situ X-ray and Raman scattering techniques to characterize the NTN structural evolution during stretch-induced alignment. The observed inhomogeneous alignment of NTNs prompts the need for a method that accurately determines the degree of nanotube alignment in bulk materials. A method that combines X-ray scattering and electrical anisotropy measurement was explored and proposed to determine the aligned fractions of nanotubes. Based on the characterization results, the structure-property relationship of NTNs and their electrical conductivity was studied through a 3D physics-based electrical model. The model was built in two stages. First, the structural model of NTNs was built using coarse-grained molecular dynamics, which provides high fidelity representation of the waviness, contacts and self-assembly of constituent nanotubes and ropes that originated from the van der Waals interactions. By applying tensile strains, the dynamics model also enabled the direct simulation of the dynamics of networks aligned through stretching. After the network structure was established, the simulated NTNs were translated into equivalent electrical circuits. The electrical model was developed based on the Simulation Program with Integrated Circuit Emphasis, which allows us to directly conduct device design and analysis using NTNs. This model is able to capture the effects of alignment and contact changes on the electrical properties of NTNs. Based on the understanding of the unique contact resistance dominated transport mechanism of NTNs, sensor applications of the novel materials were explored. By manipulating the tunneling barrier through either polymer molecule insertion or increasing the tunneling distances, NTNs were studied for potential applications in detecting organic solvent leakage and sensing tensile strains. Scaling-up of sensor fabrication using aligned NTNs and advanced printing technology was also explored and demonstrated.
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Date Issued: 2012
Identifier: FSU_migr_etd-6957
Format: Thesis

Title: Composites Electronic Enclosure Using Integrated Design & Manufacturing Approach and Carbon Nanotube Buckypaper Materials.
Creator: Young, Charles “Chip”, Liang, Richard, Okoli, Okenwa, Vanli, Arda, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Due to both the advantageous mechanical and unique functionality properties of advanced composite materials, it has become common practice to replace traditionally metal alloy vehicle components, with components comprised of composite materials. Though the primary functionality is that of structure, composites can be custom-tailored to possess application-specific functionalities of their alloy counterparts, such as electromagnetic interference (EMI) shielding, or high thermal and electrical...
Show moreDue to both the advantageous mechanical and unique functionality properties of advanced composite materials, it has become common practice to replace traditionally metal alloy vehicle components, with components comprised of composite materials. Though the primary functionality is that of structure, composites can be custom-tailored to possess application-specific functionalities of their alloy counterparts, such as electromagnetic interference (EMI) shielding, or high thermal and electrical conductivities. In this study, a comprehensive software environment was selected and implemented for a case study involving the design, analysis, and manufacturing of a composite electronics enclosure, with particular emphasis on the integrated design and fabrication of composite products. Additionally, the multifunctional, hybrid composite materials for such an enclosure were investigated, using carbon fiber fabric and multiple-walled carbon nanotube (CNT) buckypaper thin film as the functional materials with a bismaleimide (BMI) thermoset matrix. A study of fabricating carbon fiber-buckypaper composites was performed along with the subsequent mechanical property testing of this hybrid composite material. While developing the hybrid material, the process for manufacturing of a resin-impregnated buckypaper thin film, or buckypaper prepreg," was also achieved. The advantages of a prepreg material over dry, thin-film buckypaper are substantially improved handleability and processability, and overcoming the challenge faced with the low permeability issues encountered when utilizing buckypaper in composite fabrication.
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Date Issued: 2012
Identifier: FSU_migr_etd-6872
Format: Thesis

Title: Damage Detection in Carbon Fiber Composites Using Electrical Resistance Measurements.
Creator: Gory, Ryan, Vanli, Arda, Okoli, Okenwa, Liang, Richard, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: This thesis proposes a methodology for structural health monitoring that incorporates the inherent multi-functionality of carbon fibers. The hypothesis of the thesis is that by monitoring the electrical resistance of composite panels it is possible to detect impacts and statistically model their effects on the remaining useful service life of structures. The proposed research investigates the application of statistics-based analysis to the measured electrical resistance signals during loading...
Show moreThis thesis proposes a methodology for structural health monitoring that incorporates the inherent multi-functionality of carbon fibers. The hypothesis of the thesis is that by monitoring the electrical resistance of composite panels it is possible to detect impacts and statistically model their effects on the remaining useful service life of structures. The proposed research investigates the application of statistics-based analysis to the measured electrical resistance signals during loading. The research also investigates the use of electrical resistance as a stress sensor by monitoring the resistance of test samples under tensile loading.
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Date Issued: 2012
Identifier: FSU_migr_etd-4872
Format: Thesis

Title: Short Carbon Nanotubes and Carbon Nanofibers Composites: Fabrication and Property Study.
Creator: Koo, Ana, Liang, Zhiyong Richard, Liu, Tao, Zhang, Chun Chuck, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Carbon nanotubes (CNTs) have drawn interest for many applications since their discovery. While they provide exceptional mechanical, physical and chemical properties, several technical barriers must be overcome before these properties can be fully used. Some of such drawbacks concern length control, lack of good dispersion and poor interfacial bonding. Currently, CNTs such as single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) and carbon nanofibers (CNFs) are...
Show moreCarbon nanotubes (CNTs) have drawn interest for many applications since their discovery. While they provide exceptional mechanical, physical and chemical properties, several technical barriers must be overcome before these properties can be fully used. Some of such drawbacks concern length control, lack of good dispersion and poor interfacial bonding. Currently, CNTs such as single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) and carbon nanofibers (CNFs) are produced in lengths ranging between several to hundreds micrometers and are usually bounded into macroscopically entangled networks. This contradicts with the requirements of some applications, which in the end will benefit with short and highly dispersed CNTs in lengths of a few hundred nanometers or less, such as drug delivering and energy storage carriers. Short CNTs (s-CNTs) and CNFs (s-CNFs) can enhance the mechanical properties of a composite due to the increased interaction with the polymer matrix, through the improvement of the interfacial bonding and resin encapsulation, which is possible with existing open ends of nanotubes. Ultimately this influences the matrix's properties by affecting its chain entanglements, morphology, and crystallinity in the nanocomposite. This research is a continuous effort on nanoscale cutting and characterization of s-CNTs and s-CNFs. Moreover, this research used s-MWNTs and s-CNFs in the lengths of 200 and 500 nm to manufacture the nanocomposites. The mechanical properties of the resultant nanocomposties were characterized. The interactions of the s-MWNT and s-CNTs with epoxy resin matrix were observed using high-resolution SEM and atomic-resolution TEM. The results were compared to nanocomposites with pristine MWNTs and CNFs. In the study, four case studies were explored: 1) 200 nm s-MWNT/epoxy composites; 2) 500 nm s-MWNTs/epoxy composites; 3) 200 nm s-CNF/epoxy composites; 4) 500 nm s-CNF/epoxy composites. For all four cases the MWNT and CNF concentrations were 0.05 wt%, 0.10 wt%, and 1.00 wt%, respectively. Significant mechanical improvements were observed. The strength of the s-MWNT nanocomposite at 1.00 wt% gave a 64% improvement compared to the control sample. The highest young's modulus was also obtained in the 1.00 wt% s-MWNT (200 nm) nanocomposite, and it showed an increase of 44%. In general, the most significant improvements were seen with the s-MWNTs (200 nm) nanocomposites due to their smaller diameters and shorter length. Glass transition temperature was also studied. Finally, the interfacial bonding and interactions of the nanotube's opened ends with the resin matrix were observed through HR-SEM and atomic-resolution TEM analysis, which validated the creation of MWNT and CNF opened ends and the actual resin encapsulation inside the nanotubes' hollow structures.
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Date Issued: 2011
Identifier: FSU_migr_etd-2841
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.
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Date Issued: 2013
Identifier: FSU_migr_etd-7954
Format: Thesis

Title: Nanostructure-Based Modeling and Experimental Characterization of Electrical Conductivity of Carbon Nanotube Networks.
Creator: Li, Shu, Liang, Richard, Andrei, Petru, Wang, Ben, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Carbon nanotubes (CNTs) possess exceptional electrical properties. Networks of densely packed nanotubes that are formed by intercontacted or interconnected nanotubes and bundles were observed to form electrically conducting pathways over macroscopic dimensions and can be used for fabricating electronic devices and multifunctional composites. However, the electrical conductivity of these macroscopic networks is much less than the individual CNT's performance, primarily due to the large contact...
Show moreCarbon nanotubes (CNTs) possess exceptional electrical properties. Networks of densely packed nanotubes that are formed by intercontacted or interconnected nanotubes and bundles were observed to form electrically conducting pathways over macroscopic dimensions and can be used for fabricating electronic devices and multifunctional composites. However, the electrical conductivity of these macroscopic networks is much less than the individual CNT's performance, primarily due to the large contact resistance between nanotubes. Many factors contribute to the contact resistance, and the majority of these factors are difficult to directly measure and control due to nanoscale dimensions. The approach of physics-based simulation would help to understand the dominating factors of carbon nanotube networks (CNNs) conductivity. In this thesis work, experimental characterization of the nanostructures and electrical properties of CNNs were carried out, and an equivalent electrical circuit model of CNNs was improved to study the electrical conduction mechanism and properties. To systematically investigate the structure-property relationship between the conductivity of CNNs and their nanostructures, microscopic images of CNNs were characterized with image analysis software to obtain the CNT rope length and diameter distributions. Volume fractions of CNTs in these CNNs were also determined by experimental measurements and literature reported density of CNTs. Raman spectroscopy results were used to characterize the alignment degree of magnetically aligned CNNs. The electrical properties of CNNs, including electrical conductivity and current-carrying capacity tests, were carried out. The conductivities of various types of CNNs were obtained, including single-walled nanotubes (SWNTs), multi-walled nanotubes (MWNTs), and carbon nanofibers (CNF). CNNs of pure SWNTs possess the highest conductivity among all the networks studied. Another important electrical property, the current-carrying capacity, was also studied to understand the breakdown mechanism of CNNs. The tests were conducted to characterize the breakdown temperature and current density of the CNNs. It was determined that the breakdown of CNNs under high current stimuli was due to Joule heating. The modified electrical conductivity model is an electrical circuit simulation approach that reflects multiscale electrical conduction mechanisms and statistical nature of the CNNs. The model begins with nanoscale factors such as nanotube chirality and contact type, and then incorporates microscale factors such as dispersion and nanotube orientation, and further uses circuit computation simulation to calculate the bulk conductivity of the CNNs. Case studies were conducted to first validate the model and then reveal the structure-property relationships of different types of CNNs, including the effects of CNT orientation and chirality on the conductivity of the CNNs. The experimental results and developed model can be used to design and optimize CNNs for electrical applications.
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Date Issued: 2009
Identifier: FSU_migr_etd-7182
Format: Thesis

Title: Theoretical and Experimental Investigation of Buckypaper: Field Emission.
Creator: Chen, Yiwen, Wang, Ben, Zhang, Mei, Brooks, James S., Liang, Richard, Zhang, Chuck, Vanli, O. Arda, Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: Many researchers regard carbon nanotube backlight units (CNT-BLUs) as a potential candidate for the liquid crystal display (LCD) industry. CNT buckypapers were tested as surface luminary sources for CNT-BLU applications. The field emission properties, durability and repeatability of a single-walled Carbon nanotube (SWCNT) buckypaper was studied for developing CNT-BLU. This study reports a laser irradiation process to enhance the field emission properties of buckypaper, which is a thin sheet...
Show moreMany researchers regard carbon nanotube backlight units (CNT-BLUs) as a potential candidate for the liquid crystal display (LCD) industry. CNT buckypapers were tested as surface luminary sources for CNT-BLU applications. The field emission properties, durability and repeatability of a single-walled Carbon nanotube (SWCNT) buckypaper was studied for developing CNT-BLU. This study reports a laser irradiation process to enhance the field emission properties of buckypaper, which is a thin sheet of high-loading carbon nanotube networks. A scanning laser treated selected regions of the buckypaper to activate CNT emitters. This post-process causes a decrease in turn-on field and increases in the field enhancement factor ( and #946;), luminance intensity and uniformity of buckypaper emitters. The phosphorescence luminance intensity and uniformity of buckypaper emitters were measured and characterized. These exellent properties and performance were achieved by adjusting machining parameters of laser power, laser lens motion speed, laser resolution. Design of Experiment (DOE) methodology provided a method to rapidly search the feasible laser parameter setting for processing buckypaper and improving field emission properties within fewer experimental runs. DOE results indicated the proper laser treatment power density was 0.9 W/cm2. Furthermore, the effects of the laser treated emitter density was investigated under the same laser power density as the DOE results. The CNT emitter's altitude, diameter and spacing were characterized through an optics analysis after laser treatment. The emitter spacing directly impacted emission results when the laser power and treatment time were fixed. The increasing emitter density gave rise to an enhanced field emission current and luminance. However, a continuous and excessive increase of emitter density with spacing reduction generated a screening effect. As a result, the extended screening effect from the smaller spacing eventually crippled the field emission effectiveness. From luminance intensity and uniformity of field emission, the optimal ratio of average emitter altitude to emitter spacing was 3.4. The high effective buckypaper is suggested to have a density of 50 50 emitters/cm2, which presents an effective field enhancement factor of 3721 and a moderated screening effect of 0.005. Proper laser treatment appears to be an effective post-treatment process for optimizing field emission and luminance performance for a buckypaper cold cathode.
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Date Issued: 2010
Identifier: FSU_migr_etd-7113
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.
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Date Issued: 2013
Identifier: FSU_migr_etd-7772
Format: Thesis

Title: Thermal Management Composites Utilizing Carbon Nanotubes and High-Conducting Carbon Fibers: Design, Fabrication and Characterization.
Creator: Zimmer, Michael Makoto, Liang, Zhiyong Richard, Wang, Ben, Brooks, James, Zhang, Chun (Chuck), Department of Industrial and Manufacturing Engineering, Florida State University
Abstract/Description: The focus of the dissertation is to find solutions to increase the through-thickness thermal conductivity of fiber-reinforced polymer matrix composites (PMC). The objective is to explore novel concepts and new approaches to improve the through-thickness thermal conductivity up to 30W/mK for PMCs. First, this research involves understanding the principles of thermal transport in composite and nanocomposite materials. Then the research proceeds to model and design high thermal conducting...
Show moreThe focus of the dissertation is to find solutions to increase the through-thickness thermal conductivity of fiber-reinforced polymer matrix composites (PMC). The objective is to explore novel concepts and new approaches to improve the through-thickness thermal conductivity up to 30W/mK for PMCs. First, this research involves understanding the principles of thermal transport in composite and nanocomposite materials. Then the research proceeds to model and design high thermal conducting composites and develop fabrication processes and characterization methods for functioning prototype materials. PMCs are advantageous for their light-weight, excellent strength and high modulus properties. However, due to insulation nature of polymer resin matrices, their bulk composites demonstrate poor through-thickness thermal conductivity making it unsuitable for applications that undergo thermal loads requiring a means for adequate heat dissipation. The research has carried out four technical approaches to achieve high through-thickness thermal conductivity. 1. Conductive Resins: Increasing the thermal conductivity of the matrix would increase the bulk through-thickness thermal conductivity. Experiments have been done using conductive fillers such as metallic nanoparticles and carbon nanotubes. Results have shown increase in the thermal conductivity but with the disadvantage of increased matrix viscosity making the fabrication process difficult. The thermal conductivity increases, however, is not adequate to achieve the objective solely. 2. Stitch Method: This method applies a continuous conductive path by stitching or inserting high conducting materials such as metal wires, high conducting carbon fiber or high conducting carbon yarns in the through-thickness direction of the composites. Experimentally, this method has proven to show a 27 fold increase in the through-thickness thermal conductivity at low volume fraction percentage of 5% with copper wire and 3.5 fold increase using K-1100 carbon yarn. 3. Long MWNT: Long MWNTs should create a conductive microstructure between fiber layers in composites. Providing conductive links improve the thermal transport of phonons, long MWNTs should more effectively provide thermal transport between fiber layers. However, the experimental results have yet to yield any improvements in the thermal properties of the composites. 4. Buckypaper: The use of thin film of dense nanotube networks or buckypapers is to improve the thermal connections between fiber layers as an interlayer material. If the buckypaper can make multiple connections between fiber layers, the nanotube network can be used to facilitate thermal transportation. However, the use of buckypaper has shown to have a reduced thermal conductivity value than that of a composite without buckypaper. Buckypaper in the experiment create resin rich areas between layers. Modeling efforts were performed to understand thermal transport mechanism, find solutions and predictions to through-thickness thermal conductivity of the multiscale composites. Micromechanical models were used to predict thermal property values for conductive resins as well as nanoparticle/fiber multiscale composites. Results show that only a few models prove useful with close predictions to experimental data. On the other hand, finite element modeling (FEM), allows the exploration of the critical nanoparticle/fiber interactions and their effects on thermal properties of the resultant composites. The FEM results show that it is the interconnections between nanoparticle and fibers, rather than concentration of conductive fillers, significantly impact the through-thickness thermal conductivity in PMCs, where continuous thermal pathways were the most important for performance improvement. Discontinuous pathways of nanotubes and conducting materials showed very limited or no effects on thermal conductivity improvements. These results provide viable information for future design and fabrication of high through-thickness thermal conductivity composite materials for thermal management multifunctional applications.
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Date Issued: 2009
Identifier: FSU_migr_etd-7265
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.
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Date Issued: 2014
Identifier: FSU_migr_etd-9011
Format: Thesis

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