Author ORCID Identifier
0000-0001-8757-7504
Document Type
Dissertation
Date of Award
5-31-2022
Degree Name
Doctor of Philosophy in Mechanical Engineering - (Ph.D.)
Department
Mechanical and Industrial Engineering
First Advisor
I. Joga Rao
Second Advisor
Ian Sanford Fischer
Third Advisor
Pushpendra Singh
Fourth Advisor
Zhiming Ji
Fifth Advisor
Samuel Lieber
Abstract
Shape memory polymers (SMPs) are a class of soft active materials that have the ability to retain one or multiple temporary shapes and exhibit deformation as a response to stimuli. The temporary shapes involved can be very complex, but SMPs can recover large amounts of strains compared to other smart materials. They have a wide range of applications, and their mechanism can be easily altered. Hence, there is an increasing need to model their behavior.
This study discusses the behavior of a thermally activated subclass of SMPs in which the temporary shape is fixed by a crystalline phase and the return to the original shape is due to the transition of this crystalline phase, as well as a light-activated subclass of SMPs in which the temporary shape is fixed by photo-reversible covalent crosslinks Its thermo-mechanical behavior is simulated using a framework based on the theory of multiple natural configurations. Viscoelastic effects are incorporated using a rate type model along with the anisotropy of the crystalline phase.
The model is applied to boundary value problems of homogeneous deformations such as uniaxial extension of dual shape and triple shape memory polymers under controlled stress and strain conditions. The model is also applied to boundary value problems related to inhomogeneous deformations such as circular shear, inflation, and extension of a hollow cylinder. Uniaxial extension of photo-adaptable thermally activated shape memory polymers is also solved numerically and implemented in finite element software Abaqus. The effects of parameters such as temperature, external stress, crystallinity, shear modulus, and relaxation time on the nonlinear deformation are studied. The theory is numerically implemented by writing a user-defined material subroutine (UMAT) for the widely used finite element program Abaqus. The results are consistent with the experimental data and show how these parameters influence the complicated thermo-mechanical behavior and shape memory effect.
Recommended Citation
Prasad, Aayush, "Constitutive modeling and numerical simulations related to dual and triple shape memory polymers" (2022). Dissertations. 1923.
https://digitalcommons.njit.edu/dissertations/1923
