Characterization and Modeling of Deformable Soils for Tire Performance Simulations

Abstract

The accurate prediction of tire-soil interaction plays a crucial role in the optimization and design of off-road machinery used for agricultural, defense, construction, and mining applications. The tire-road interaction studies focus solely on road roughness and friction between rubber and asphalt while assuming the road surface to be rigid. However, for tire-soil interaction, the deformations occurring in the soil must be accounted for in predicting the tire performance. The modeling of soil presents significant challenges because of its non-linear and complex behavior, which depends on multiple external and internal factors. This thesis focuses on developing a methodology for physics-based modeling of soil for accurate tire performance simulations and its validation. For this study, one cohesive (sandy loam) and one non-cohesive soil (dry sand) are used. The material model parameters of both soils are identified, verified, and validated using a series of laboratory and in-situ test experimental data and numerical simulations. Later, the numerical simulations of tire-soil interaction for both soils are performed using one meshed (Coupled Eulerian-Lagrangian) and one meshless (Smooth Particle Hydrodynamics) method are performed. The results of the numerical simulations are validated with the experimental data obtained at different normal loads (3 kN - 7 kN) and slip ratios (-10% - 40%). Further, the benchmarking of both the numerical methods used is done in terms of relative computational efficiency and accuracy. The cap plasticity material model with strain hardening showed higher accuracy in predicting soil shear strength and failure compared to other material models. For the tire-soil interaction studies, the SPH method overall has a better correlation with the experimental data compared to the CEL method. Meanwhile, the CEL method has higher computational efficiency. The results of the study provide significant insights into the physics of the tire-soil interaction and provide direction for future researchers.