Behaviour of the heterogeneous glassy polymers:: Computational modelling and experimental approach

In the present study we have investigated the mechanical behaviour of multi-phase solid materials by using the micro-macro computational approach. Spherical rubber particles embedded in amorphous glassy polymer matrix are taken into account as the heterogeneous composite system. In order to predict the micromechanical deformation behaviour of the composite, we propose a combination of an appropriate elastic-viscoplastic constitutive equation describing the nonlinear behaviour of the polymeric matrix with a hyperelastic model for the rubbery phase. The resulting hyperelastic-viscoplastic model accurately predicts the intrinsic strain rate, the temperature dependent behaviour and the subsequent strain hardening of rubber modified polymer. The representative volume element (RVE) selected in the homogenisation process by finite element analysis, is constructed by assuming local spatial periodicity of the microstructure. The macroscopic stresses and strains are obtained by averaging RVE stress-strain field. The validity of both homogenisation procedure and the constitutive model is achieved by comparison with experimental data for uniaxial compression tests on PMMA and RT-PMMA at different temperatures. A fair agreement is obtained between numerical and experimental results. (C) 2007 Elsevier Ltd. All rights reserved.