THE LARGE-STRAIN COMPRESSION, TENSION, AND SIMPLE SHEAR OF POLYCARBONATE

Polymeric materials subjected to large strains undergo an evolution in molecular orientation. The developing orientation and corresponding s trengthening are highly dependent on the state of strain. In this pape r, we examine and compare the very different stress-strain results of polycarbonate produced from four types of mechanical testing: uniaxial compression, plane strain compression, uniaxial tension. and simple s hear. These tests produce different states of orientation within the m aterial and, in the case of simple shear, the principle axes of orient ation rotate during the deformation. The ability of the recent constit utive model of Arruda and Boyce (1992) to predict the observed behavio r is evaluated. The model has been incorporated into a finite element code in order to properly simulate the material behavior during the in homogeneous deformations of tension (cold drawing) and simple shear. T he material properties of the model are obtained from the uniaxial com pression test and the model is then found to be truly predictive of th e other states of deformation demonstrating its fully three dimensiona l capability. The disadvantages of the tensile and simple shear tests for obtaining the data needed to accurately quantify the large strain material behavior of polymers are shown and discussed.