Triple Shape Memory Polymers: Constitutive Modeling and Numerical Simulation

Recently, triple shape memory polymers (TSMPs) have been discovered; these materials can be programmed to switch between three distinct shapes. Previously, we introduced a model to describe the mechanical behavior of TSMPs; however, the earlier study was limited in scope to simple cases of uniaxial deformation. In this work, we build upon our prior work, and develop robust numerical methods and constitutive equations to model complex mechanical behavior of TSMPs in inhomogeneous deformations and loading conditions using a framework based on the theory of multiple natural configurations. The model has been calibrated to uniaxial experiments. In addition, the model has been implemented as a user material subroutine (UMAT) in the finite element package ABAQUS. To demonstrate the applicability of the developed constitutive model, we have numerically simulated two cases of three-dimensional bodies undergoing triple-shape cycles; triple-shape recovery response of a complex TSMP geometry and the triple-shape recovery response of a stent when it is inserted in an artery modeled as a compliant elastomeric tube.