Abstract
Stress-strain curves of polycarbonate (PC) are determined in a wide range of strain rates under conditions of uniaxial strain. The effect of strain rate on the stress is investigated under these conditions. A plate impact testing apparatus, a drop hammer testing machine and a universal testing machine are used for the high strain rate (10^6 to 10^7 s^<-1>), medium strain rate (10^2 s^<-1>) and low strain rate (10^<-3>s^<-1>) tests, respectively. The plate impact test is used to obtain stress-strain curves for PC undergoing uniaxial strain. Stress-time histories are obtained in PC at impact velocities of 718 and 540 m/s using polyvinylidene fluoride (PVDF) gauges. Lagrangian analysis is used to extract strain-time histories under conditions of uniaxial strain from the experimental stress data. The drop hammer testing and universal testing methods combined with an extrapolation procedure are used to determine the stress-strain behaviors of PC under conditions of uniaxial stress. The stress-strain curves at medium and low strain rates in uniaxial strain are constructed on the basis of the Wood's equation from the uniaxial stress data. The strain-rate sensitivity of the stress is found to increase when the strain rate is raised into the shock loading regime.
