A model for predicting the evolution of damage in viscoelastic particle-reinforced composites

A viscoelastic cohesive zone model is employed within the framework of a finite element code to analyze a two-phase viscoelastic particle-reinforced composite material consisting of a relatively stiff aggregate embedded in a copolymer binder. The composite of interest, LX17, is noted to have a very large aggregate volume fraction and as such, aggregate grain boundaries were generated within finite element meshes along which viscoelastic cohesive zones have been embedded to model the binder. It has been observed experimentally that the majority of damage in LX17 occurs within the binder, and thus, a damage evolution law has been applied to the viscoelastic cohesive zones that is phenomenological in nature. The responses obtained for the composite from the FEM analysis are then compared to the experimental data compiled by Lawrence Livermore National Labs for various constant strain rate tests conducted by Groves and Cunningham [Tensile and compressive mechanical properties of billet pressed LX17-1 as a function of temperature and strain rate. UCRL-ID-137477. Internal report prepared for Lawrence Livermore National Laboratory, Livermore, CA].