Date of Award

Spring 1-1-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

First Advisor

H. Jerry Qi

Second Advisor

Martin L. Dunn

Third Advisor

Yifu Ding

Fourth Advisor

Mark P. Stoykovich

Fifth Advisor

Jianliang Xiao

Abstract

This dissertation presents studies with a combination of experiment, theory, and simulation on a broad range of polymeric material systems (both established and emerging), that exhibit the shape memory (SM) effect. The goals of the studies are to understand complex thermomechanical behaviors of shape memory polymers (SMPs), develop constitutive models to describe the behaviors and use the developed models to advance the development and deployment of SMPs. The general approach used in the studies is independent of the material system and consists of: i) sample fabrication and thermomechanical experiments including dynamic mechanical analysis (DMA), stress-strain behaviors and thermal strain tests; ii) development of micromechanics-inspired constitutive models incorporate large deformation and anisotropy; iii) comparison of experiment and theory and parametric studies. The studies have resulted in many major/key findings: a) for shape memory elastomeric composites (SMECs) consisting of elastomeric matrix and crystallizable fibers, a sophisticated thermomechanical constitutive was developed to describe the shape memory behaviors based on the melt-crystal transition of the fibers. b) For triple shape polymeric composites (TSPCs) consisting amorphous SMP based matrix and crystallizable fibers, a constitutive model separately considering the glassy transition of the matrix and the melt-crystal transition of fibers, was developed to describe triple shape memory behaviors of the composites. c) For printed shape memory composites (PSMCs), the fabrication approach for anisotropic shape memory elastomeric composites (ASMECs) was developed. A thermomechanical constitutive model was also built to describe the fiber orientation dependent shape memory behaviors.

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