Accelerated simulations of direct shear tests by physics engine

Abstract

Physics engines, originally developed to simulate physical and mechanical processes in modern video games, are increasingly used as a scientific computational platform in many disciplines due to their high computational efficiency. This study explores the feasibility of using an open-source physics engine, Project Chrono, to simulate direct shear tests. This study develops a series of pre-processing, servo-controlling, and post-processing functions in Project Chrono to generate soil specimens with designed packing densities, perform direct shear tests, and output simulation results including stress–strain relations, fabrics, and force chains. To determine inter-particle contact forces, typical DEM codes use soft contact models, while most physics engines use hard contact models. The hard contact model enables physics engines to use large time steps in iterations without affecting the numerical stability and simulation accuracy, which remarkably reduces simulation time compared with typical DEM codes. Based on systematical comparisons between simulation results of two contact models, this study demonstrates that the hard contact model can yield the same direct shear test results observed in soft contact model simulations, but is ten times faster than the soft contact model for simulating the same number of particles. This study may provide DEM modelers with the physics engine as one more option for soil behavior simulation.