Critical Material Parameters for Modeling Devices Made from an Epoxy-Based Shape Memory Polymer

Abstract

Differential scanning calorimetry (DSC), simple tension, and planar tension experiments were used to investigate the behavior of an epoxy-based shape memory polymer (SMP) system. DSC results found the mixture had consistent glass transition at 70° C, which agreed with prior research with this formulation.

Simple tension experiments were consistent with nonlinear elastic behavior and FEA analysis agreed with the experiments. However, the nonlinear elastic model did not predict the performance found in planar tension.

Planar tension results were unexpected. The stress/strain response was sigmoidal with a significant plateau in stress followed by rising stress to failure. The standard 10:1 gage width/gage length ratio seemed to over constrain the material. The strain to failure was small, and insufficient for extracting hyperelastic parameters. Using narrower gage width specimens, or perhaps a new specimen design, would benefit modeling and analysis for this material.