Predicting shape memory characteristics of polyurethane in three-point bending deformation

Abstract

As a kind of an exceptional material, the temperature-responding shape memory polymer can fix a temporary shape when cooled down and recover to its original shape when reheated up. Several models have been developed to describe the process. In the present work, we use the generalized Maxwell model to predict the shape memory characteristics of polyurethane in three-point bending deformation by means of three-dimensional finite element simulation. The deformation-temperature-stress behavior is obtained numerically. The results reveal that under the condition of accelerating reheating rates at the stage of stress-free recovery, the maximum recovery rate occurs at higher temperature whereas the recovery ratio decreases. When the deformation degree enlarges, the maximum recovery stress increases in the situation of constrained recovery. The micro-motion theory of polymer segments is used to explain the characteristics in the shape memory cycle. The simulated results agree well with previous researches, which demonstrate that the simplified model and the numerical simulation method are helpful for both scientific research and engineering development about shape memory polymers.

A comprehensive review on thermomechanical constitutive models for shape memory polymers

“…They simulated the torsion of a rectangular bar in a shape recovery stage. Yu et al (2015Yu et al ( , 2016, Wang et al (2014bWang et al ( , 2014c, and Mailen et al (2019) employed the same linear model of the generalized Maxwell thermo-viscoelastic model, which was actually a simplified version of the nonlinear model of Westbrook et al (2011a) in different problems. It is worth noting that Yu et al (2016) examined the cyclic behavior of an amorphous thermoset epoxy putting to use the same generalized Maxwell-Wiechert model.…”