Tire-Soil Modeling for Vehicle Rollover Over Sloped Compressible Terrains

Military vehicles have been experiencing high rollover rates over the last few years of deployment. There have been several hundred rollovers, of which approximately fifty percent are categorized as fall based. Fall based rollover occurs when the road gives way underneath the vehicle on one side as the soil is unable to support the vehicle load. To reduce fatalities, a real-time driving simulator can be used to simulate fall-based rollover for the driver training as well as for validating the effectiveness of advanced suspension technologies. The driver training can help prepare drivers with the varying degrees of terrain difficulties, by applying optimal steering and speed strategies in a simulated environment. The fall-based rollover occurs mainly due to combination of the tire sinkage and the lateral bulldozing. In the current research, equations for the tire-soil model are developed based on the Bekker’s equations and Mohr-Coulomb equations that compute the tire sinkage into the soil, the lateral and longitudinal forces from the soil deformation, rolling resistance due to the soil compaction, and the lateral plowing effects. The tire-soil model is incorporated into a commercial real-time multi-body code to simulate fall-based rollovers for various slopes and soil conditions. Results indicate rollover propensity changes depending the type of soil and the steering strategy used.