Simulation of Split Hopkinson Pressure Bar Tests on Sands Using the Discrete-Element Method

Abstract

Split Hopkinson pressure bar (SHPB) tests have been used extensively to study the stress–strain behavior of sand under high strain-rate conditions. However, the low impedance of sand leads to specimens not attaining stress equilibrium; therefore, the reported results from SHPB tests, assuming stress equilibrium, might be invalid at low stresses. In this study, a model based on the discrete-element method (DEM) was developed to model SHPB tests on dry sand reported in the literature. The DEM model was calibrated and validated by comparing the simulated and reported stress–strain responses. The validated model was subsequently used to conduct a parametric study to investigate the effect of particle rotational resistance on the stress–strain response and stress equilibrium of the specimens. It was found that the DEM specimens did not attain strict stress equilibrium; however, the stress–strain responses obtained using the transmission bar stress (assuming stress equilibrium) and the average stress between the transmission and incident bars (assuming stress nonequilibrium) were within the error bar reported in the experiment. The parametric study showed that a higher particle rotational resistance resulted in a stiffer stress–strain response, and particle rotation meaningfully contributed to the sand response during SHPB tests.