A unified finite strain visco-elastic visco-plastic constitutive model for a thermosetting polymer from low to high strain rates: Experiments, Validation and Bayesian optimization

A thermosetting polymer exhibit phase transitions from low strain rate to high strain rate loading, even at high temperatures. In this work, a unified finite strain visco-elastic visco-plastic (VE-VP) constitutive model considering temperature and strain-rate effects is theoretically developed and numerically implemented in a commercial software by means of a user defined subroutine to characterize observed mechanical response from low to high strain rate, where the phase transition can be characterized by a change in parameter quantities. In order to solve the problem of multi-parameters identification from the VE-VP model (more than 10 parameters), a multi-stage physical interpretation Bayesian optimization (MSPI-BO) framework has been proposed, accounting for the physical reasonability when calibrating material properties, and then giving the explicit mathematical expressions of the material parameters variation with temperature. The results show the VE-VP constitutive model using the MSPI-BO calibrated material parameters can well illustrate the mechanical response of polymer at different temperatures and strain rates. The proposed MSPI-BO approach in this paper provide a new perspective and inspiration for data-driven computational mechanics.