The automotive industry is currently interested in using lighter and impact resistance materials in vehicular systems, as they would make vehicles more fuel efficient without compromising safety standards. In this context, polymeric materials are a good option for this application.
The work describes the development of a material model based on a thermodynamic approach with internal state variables for amorphous polymers. The material model, which follows current methodology used for metals, departs from spring-dashpot based models generally used to predict the mechanical behavior of polymers. Regarding the choice of internal state variables, we used a hierarchical multiscale approach for bridging mechanisms from the MD simulations to the continuum model. The constitutive model applied a formalism using a three-dimensional large deformation kinematics and thermodynamics framework. The model is then validated by compression and impact tests at different strain rates on amorphous polymers. The model prediction shows good agreement with experimental testing.