Prediction of the large strain mechanical behaviour of heterogeneous polymer systems by a multi-level approach

Shear band formation in heterogeneous tensile bars was studied using an accurate homogenization method that allows for a numerical coupling between the microscopic and macroscopic stress-strain behavior. The procedure is based on a classical homogenization theory, assuming local spatial periodicity of the microstructure, and supplies a consistent objective relation between the local macroscopic deformation and the microstructural deformation of a spatially periodic representative vol. element (RVE), representing the local microstructure. The method was used to predict the influence of the microstructure on localization phenomena in plane strain hour-glass-shaped polycarbonate specimen with different vol. fraction of non-adhering low-modulus rubbery particles. An irregular particle distribution seems to promote deformation spreading over the sample, which leads to enhancement of toughness of heterogeneous polymer systems by the addn. of easily cavitating rubbery particles