Material characterization and nonlinear viscoelastic modelling of epoxy based thermosets for automotive application

This paper presents material characterization utilizing static tensile tests until failure and static tests with relaxation segments until failure for commercially available molding compound. In order to model the material behavior quantitatively a non-linear viscoelastic (NLVE) Bergstrom-Boyce model (BB) is proposed. Material constants of the BB model are optimized utilizing commercially available code optiSLang. In this paper a detailed optimization scheme is presented, including regression and sensitivity analysis. The NLVE model is shown to improve the predictions of the experimental results compared to state-of-the-art linear viscoelastic (LVE) material model. Thus, the BB model is proposed to be used for time, temperature and stress dependent behavior of polymers.