Date of Award
2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy in Mechanical Engineering and Applied Mechanics
Department
Mechanical, Industrial and Systems Engineering
First Advisor
Arun Shukla
Abstract
Chapter 1: Multifunctional composites and smart textiles are an important advancement in material science, offering a variety of capabilities that extend well beyond traditional structural functions. These advanced materials are poised to revolutionize applications across a wide range of industries, including aerospace, healthcare, military, and consumer electronics, by embedding functionalities such as structural health monitoring, signal transmission, power transfer, self-healing, and environmental sensing. This review, which draws on insights from various disciplines, including material science, engineering, and technology, explores the manufacturing techniques employed in creating multifunctional composites, focusing on modifying textiles to incorporate conductive fibers, sensors, and functional coatings. The various multifunctional capabilities that result from these modifications and manufacturing techniques are examined in detail, including structural health monitoring, power conduction, power transfer, wireless communication, power storage, energy harvesting, and data transfer. The outlook and potential for future developments are also surveyed, emphasizing the need for improved durability, scalability, and energy efficiency. Key challenges are identified, such as ensuring material compatibility, optimizing fabrication techniques, achieving reliable performance under diverse conditions, and modeling multifunctional systems. By addressing these challenges through ongoing research and further innovation, we can significantly enhance the performance and utility of systems, driving advancements in technology and improving quality of life.
Chapter 2: In this study, damage mechanisms and the piezo-resistance response of glass/carbon intralaminar hybrid composites are examined under blast loading conditions. Two-ply orientations are considered, namely a repeating ((G45C45)R) and an alternating ((G45C45)A) ± 45 deg glass/carbon layers, along with three boundary condition configurations: simply supported, partially fixed, and fully fixed are applied. A shock tube apparatus and the three-dimensional digital image correlation technique are utilized to investigate the interaction of shock waves with the composites and gather a comprehensive deformation field during the loading. A modified four-probe resistivity measurement method is implemented to comprehend the piezo-resistance response associated with damage evolution. The results underscore the substantial influence of boundary conditions on the blast mitigation capacity of the composites. Analysis following the experiments reveals that the damage to the specimens primarily involves the fracture of fibers accompanied by internal delamination. Thermal imaging of the tested composite specimens provides enhanced insight into the precise occurrences of internal fiber breakage and delamination. Composites of (G45C45)A type demonstrate an increased energy dissipation ranging from 18% to 33% compared to (G45C45)R composites, depending on the specific boundary conditions among the three types considered. Furthermore, the findings indicated a strong correlation between changes in piezo-resistance and the fracture of carbon fibers, coupled with the sustained deformation of the composites. Notably, (G45C45)A composites exhibited 100-300% higher change in piezo-resistance compared to (G45C45)R composites depending on the boundary condition configurations, indicative of the superior damage-sensing capabilities of the former.
Chapter 3: This study evaluates the performance of composite structures with embedded conductive yarns during shock loads to create a multifunctional system for immediate failure detection. The scalable sensing yarns were made by braiding Kevlar fibers with Nitinol fibers and then integrating them into a carbon/epoxy prepreg. The multifunctional structure was subjected to a Mach 2 air blast load using a shock tube apparatus. The embedded sensor yarns were used to record their electrical performance, while Digital Image Correlation captured full-field displacements, velocities, and strains. In addition, pressure transducers measured shock event pressures. The results revealed that through-thickness failure of the laminated composite occurred at approximately 2.5% strain, which was visually observable. However, the embedded sensor exhibited out-of-range electrical measurements at around 1.5% strain, even though no visible structural damage was present. This demonstrates the embedded sensing yarns' ability to detect delamination-type failures by responding to interlaminate damage, highlighting their advantages over conventional external sensors. Similarly, the gauge factor for the fiber system was determined to be 1.89 ± 0.07. This multifunctional system shows great potential for enhancing composite structure safety and performance in high-performance aerospace applications and offering real-time structural health assessment.
Chapter 4: This study evaluates the power transmission of multifunctional composites with embedded conductors. The electrical conductors were constructed by braiding copper strands with Para-aramid fibers into a tape configuration, and then placing these tapes within carbon/epoxy prepregs to create a multifunctional structure. Experiments were performed on these multifunctional composites under tensile loading conditions. During experimentation, the conductive tapes were incorporated within an electrical bridge to record their resistance change as a function of mechanical strain. The Digital Image Correlation (DIC) technique was used to obtain in-plane displacements and strains as a function of time. In addition, low-speed flight condition experiments with an airfoil shape composite system were carried out in a wind tunnel to study the temperature performance of these structures while under high currents. Computational models were then created to expand the experimental efforts and evaluate the system’s multiscale performance. Experimental results show that the mechanical load on the conductive tape is mainly carried by the Para-aramid yarns, leading to a relatively consistent electrical performance and airflow over the wind foil providing efficient power transmission. Lastly, the computational models showed consistency in the electrical/mechanical results and established a framework for analyzing multi-functional structures (MFS).
Chapter 5: This chapter investigates the electromechanical performance of textile fabric with conductive yarn elements for data transmission capabilities. Electromechanical experiments were conducted to evaluate the electrical response of copper yarn elements stitched axially to the textile fabric while assessing the mechanical response of the system during tensile tests under axial loading. The results indicated that the yarn element exhibited low electromechanical coupling below 1.5% strain, making it suitable for consistent electrical performance during low mechanical strain conditions. Computational models were also developed and correlated with the experimental results of the conductive yarn. The computational model was then expanded to investigate the effect of the braiding angle in the braiding system, providing insights into how these parameters influence the system’s performance. Overall, this research contributes valuable insights into the electromechanical behavior of textile fabric with conductive yarn elements and presents a framework for optimizing data transfer capabilities in e-textiles and smart textile applications. The findings open opportunities for further advancements in the design and engineering of functional textiles for a wide range of applications.
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Recommended Citation
Chaudhary, Birenda, "PERFORMANCE OF MULTIFUNCTIONAL COMPOSITE STRUCTURES IN STATIC AND DYNAMIC CONDITIONS" (2024). Open Access Dissertations. Paper 1699.
https://digitalcommons.uri.edu/oa_diss/1699