Experimental study of the polycarbonate behaviour during complex loadings and comparison with the Boyce, Parks and Argon model predictions

The aim of this paper is to characterise the mechanical behaviour of polycarbonate in complex loadings through experimental investigations. Various strain paths and histories have been experimented in compression such as loading-unloading for different strains, repeated loading-unloading with various dwell times and stress levels and non-radial loading tests. All these experiments have been carried out at a constant nominal strain rate (0.001/s) and room temperature. Elastic, permanent and recoverable strain components have been identified and their strain rate evolution estimated. The influence of dwell time and stress level on the anelastic deformation has also been studied. The non-radial experiments have emphasised the strongly anisotropic behaviour of polycarbonate. Finally, the results of these tests are compared to the well known Boyce, Parks and Argon (BPA) [Boyce MC, Parks DM, Argon AS. Large inelastic deformation of glassy polymers Part 1: rate dependent constitutive model. Mech Mater 1988:7:15-33, [11] constitutive model. The major discrepancies observed concern the absence of simulated permanent strain and the incorrect description of the anelastic strain. Besides, the predicted anisotropic response of polycarbonate (PC) does not match the experimental observations. The role of internal stresses, induced by deformation process, on polycarbonate behaviour is pointed out. (C) 2008 Elsevier Ltd. All rights reserved.