The biaxial deformation and yield behavior of bisphenol‐a polycarbonate: Effect of anisotropy

Abstract
The biaxial tension stress‐strain‐yield behavior of glassy bisphenol A‐polycarbonate has been investigated at constant octahedral shear stress rate and at 25°C and −40°C. The specimens possess a small amount of anisotropy. Hill′s criterion for yielding of anisotropic materials is modified to take into account the sensitivity of the yield locus to the hydrostatic stress component. This modified yield criterion fits the 25°C data quite well. However, the data at −40°C cannot be fitted using reasonable parameters.