Tungsten alloy impact fracture for frangible armor piercing

Abstract

This paper presents experimental and numerical studies of tungsten alloy fragmentation caused by impact loading. Impact loading is a complex mechanics including dynamic hardening and fracture coupled with a wide range of strain, strain rate, and temperature. In order to obtain the dynamic hardening behavior from low to high strain rates, compression tests have been conducted with the INTRON 5583 and the Split Hopkinson Pressure Bar testing machines. Taylor impact tests are also carried out at various impact velocities to evaluate the fragmentation. Considering the fragmentation tendency of tungsten alloy in this study, it could be utilized for the penetrator of FAP projectile. For the further investigation, finite element analysis is performed to predict the dynamic behaviors by using Lim-Huh hardening model and Mohr-Coulomb(MC) fracture model. In the MC fracture model, the mean stress concept is introduced. The fracture model parameters are calibrated using inverse engineering of the test results. The analysis successfully predicts the deformation and fragmentation according to the impact velocity. It is shown that the stress-based Mohr-Coulomb fracture model successfully predicts the direction of crack propagation and fragment size tendencies.