Type of Document Dissertation Author Qiu, Jingjing Author's Email Address email@example.com URN etd-06242008-172901 Title Multifunctional Multiscale Composites: Processing, Modeling and Characterization Degree Doctor of Philosophy Department Industrial and Manufacturing Engineering, Department of Advisory Committee
Advisor Name Title Ben Wang Committee Co-Chair Chuck Zhang Committee Co-Chair David Jack Committee Member Subramanian Ramakrishnan Committee Member Zhiyong Liang Committee Member Keywords
- Multifunctional Materials
- Multiscale Composites
- Carbon Nanotubes
Date of Defense 2008-06-17 Availability unrestricted AbstractCarbon nanotubes (CNTs) demonstrate extraordinary properties and show great promise in enhancing in-plane and out-of-plane properties of traditional polymer/fiber composites and enabling functionality. However, current manufacturing challenges hinder the realization of their potential.
In the dissertation research, both experimental and computational efforts have been conducted to investigate effective manufacturing techniques of CNT integrated multiscale composites. The fabricated composites demonstrated significant improvements in physical properties, such as tensile strength, tensile modulus, inter-laminar shear strength, thermal dimension stability and electrical conductivity. Such multiscale composites were truly multifunctional with the addition of CNTs.
Furthermore, a novel hierarchical multiscale modeling method was developed in this research. Molecular dynamic (MD) simulation offered reasonable explanation of CNTs dispersion and their motion in polymer solution. Bi-mode finite-extensible-nonlinear-elastic (FENE) dumbbell simulation was used to analyze the influence of CNT length distribution on the stress tensor and shear-rate-dependent viscosity. Based on the simulated viscosity profile and empirical equations from experiments, a macroscale flow simulation model on the finite element method (FEM) method was developed and validated to predict resin flow behavior in the processing of CNT-enhanced multiscale composites. The proposed multiscale modeling method provided a comprehensive understanding of micro/nano flow in both atomistic details and mesoscale. The simulation model can be used to optimize process design and control of the mold-filling process in multiscale composite manufacturing.
This research provided systematic investigations into the CNT-based multiscale composites. The results from this study may be used to leverage the benefits of CNTs and open up new application opportunities for high-performance multifunctional multiscale composites.
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