Calibration and validation of a discrete element model for sand and fine grain soil for use in vehicle mobility applications

In this paper, a procedure for calibrating a discrete element (DE) computational soil model for use in prediction of ground vehicle mobility is presented. The procedure relies on using the results of two small-scale physical soil experiments: (1) confined uniaxial compression; and (2) unconfined shear strength under different levels of normal stress and normal prestress. The confined uniaxial compression is an approximate hydrostatic compression test that is used to calibrate the DE bulk density, plastic strain, and elastic strain as a function of hydrostatic stress. The unconfined shear strength test is used to calibrate the DE inter-particle friction coefficient and adhesion stress as a function of the soil plastic strain. The test devices and experimental test procedures are presented in the paper. The DE model calibration procedure is demonstrated in the paper using two types of soils: silt–clay and sand-silt. The model is then validated by comparing its results for those two types of soil to experiment results for the following 3 tests: (1) confined shear strength test; (2) full-scale tracked vehicle drawbar-pull test; and (3) single tire drawbar-pull test. Within the middle of the slip range, the simulation results agree within ± 10 % on average with the experimental results for validation tests (2) and (3).