Simulation of Split Hopkinson Pressure Bar Tests on Sands with Low Water Content

The stress-strain response of sand at high strain rate is an important topic. However, most of the numerical studies concentrated on sands at high water content and were not able to capture the softening and subsequent stiffening stress-strain behavior observed at low water content. In this study, split Hopkinson pressure bar (SHPB) tests of sands were numerically simulated and the equations of state (EOS) at different water content were calibrated using back calculation. The back-calculated EOSs were used to calibrate a three-phase model capable of capturing the sand response at any water content. The response predicted by the three-phase model was validated by comparing the numerical and experimental stress-strain responses. A parametric study was carried out to understand the effect of interface friction and aspect ratio on the validity of the SHPB results by considering different aspect ratios and interface frictions for the specimens. The results showed that specimens with higher aspect ratio take longer time to achieve stress equilibrium, whereas specimens with interface friction never attain perfect stress equilibrium.