Multi-scale analysis of mechanical properties of amorphous polymer systems

Use of proper constitutive equations for the intrinsic behaviour of glassy polymers (including yield, strain softening and hardening) allows nowadays for analyzing the mechanical response of homogeneous and heterogeneous polymer systems in great detail. Analyses are performed on both the periodic RVE, representative volume element, level and, via a MLFEM, multi-level finite element method, also on the macroscopic level of e.g. a notched, scratched tensile test bar. Introduction of a failure criterion, in this case the critical tri-axial stress that initiates crazing, allows for the prediction of brittle-to-tough transitions, both as a function of temperature as well as of the absolute critical local material thickness. The analyses give clear suggestions towards possible directions to optimize the microstructure in heterogeneous polymer systems in order to obtain the ultimate toughness of polymers.