Taylor impact response of tungsten heavy alloy: Multi-scale experiments and modeling

This study examines the impact response and fracture behavior of 8 mm diameter tungsten heavy alloy (WHA) rods using a combined experimental and numerical approach. To address the dimensional constraints of the raw material, characterization is performed at two scales: conventional axisymmetric specimens for large-scale tension and compression tests, and sub-8 mm flat miniature specimens to probe a wide range of stress states, from shear to biaxial tension. Quasi-static and dynamic tests reveal significant strain rate sensitivity and a pronounced strength differential effect, with compressive flow stress approximately 14% higher than in tension. Taylor impact experiments are conducted with WHA projectiles and tungsten-carbide targets at velocities up to 180 m/s. A Drucker-Prager plasticity model, combined with Swift-Voce hardening and a modified Johnson-Cook rate/temperature dependence, captures the observed plastic response. Fracture initiation is accurately described using a strain rate dependent Hosford-Coulomb model. The calibrated model successfully predicts the crack initiation under various stress states, including the loading histories during projectile impact. The results demonstrate a robust methodology for characterizing and modeling metallic projectiles, particularly when conventional testing is limited by specimen size.