Symmetrical Taylor impact studies of copper

Abstract

An integrated investigation of rod-on-rod (symmetric Taylor) impact of annealed copper was conducted using the single-stage gas-gun facility at the Cavendish Laboratory as a validation study of the Armstrong–Zerilli constitutive model, as modified by Goldthorpe. Two main techniques were used for obtaining data from the experiments: high-speed photography (up to 20 million frames s−1framing rate) and a velocity interferometer system for any reflector (VISAR). The symmetric configuration was used to minimize friction effects and eliminate target indentation seen in classic Taylor tests, where a rod is fired against a massive target block. However, the need for coaxial alignment of the two rods made the experiments considerably more challenging to perform than the classic case. The propagation of plasticity along the rods was monitored using high-speed photography and VISAR. It was found to propagate with a logarithmically decelerating velocity. The rod profiles and VISAR traces can be understood in terms of material properties such as strain hardening. No asymmetry between the responses of the two rods involved (moving and stationary) was observed within the resolution of the techniques employed. A modified Armstrong–Zerilli material model for copper predicted intermediate profiles well, but slightly overestimated the material strength.