DYNAMIC BEHAVIOUR AND DAMAGE OF POLYCARBONATE SUBJECTED TO COMPRESSIVE AND REPEATED COMPRESSIVE IMPACT LOADING

摘要

Dynamic deformation of polycarbonate (P-C), a thermoplastic polymer, has been studied using three types of compressive impact loading : the dynamic compression and dynamic repeated compression using a split Hopkinson pressure bar and normal plate impact testing. These tests allow to obtain data over a strain-rate window between 10~3 to 10~5 s~(-1). Through these data, thermo-mechanical effects due to adiabatic deformation at high strain-rate loading are observed on the stress-strain relationship as well as the evolution of the microstructure. It is also found that the mechanisms of deformation or fracture are totally different while the polycarbonate is loaded at strain-rates between 10~3 and 10~4 s~(-1) or at strain-rates in the range of 10~4 to 10~5 s~(-1). A model of constitutive equation which takes into account the above cited effects is developped.