Mesoscale simulations of pressure-shear loading of granular tungsten carbide

Numerical simulations of pressure-shear loading of a granular material are performed using the shock physics code CTH. A simple mesoscale model for the granular material is used with baseline parameters for WC taken from previous mesoscale modeling work. Simulations are performed at the same initial conditions of pressure-shear experiments on dry WC powders. Except for some localized flow regions, the simulated samples respond elastically during shear, which is in contrast to experiment. By extending the simulations to higher shear wave amplitudes, macroscopic shear failure of the samples is observed with the shear strength increasing with increasing stress confinement. The shear strength is found to be strongly dependent on the grain interface treatment and on the intragranular fracture stress. At partial compactions, transverse velocity histories show strain-hardening behavior followed by formation of a shear interface that spans the transverse dimensions of the sample. Near full compaction, no strain hardening is observed and there is a sharp transition from an elastic response to formation of an internal shear interface. Agreement with experiment is shown to worsen with increasing confinement stress with simulations overpredicting shear strengths measured in experiment.