Numerical Modelling and Simulation of the Wheel Rotation Problems by the Material Point Method

Soil-wheel interaction has been one of the fundamental research subjects in the terramechanics field. In this study the material point method (MPM) formulation is extended for the performance and mobility of unmanned wheels rotating on the soil. A new contact approach is developed for fast contact detection between rigid wheel and deformable soil. In each time step, contact background nodes are detected to define the contact elements and subsequently to determine the contact soil material points. An equivalent contact length is associated to each contact soil point and soil-wheel reaction forces are calculated. For a given angular velocity, the dynamic momentum balances (linear and angular) are solved and the motion of the wheel points is updated accordingly. Numerical simulations of a typical wheel going over the cohesive soil are presented to demonstrate the capabilities of the new approach. The soil is simulated using Mohr-Coulomb constitutive model, and the wheel is assumed as solid rigid. The wheel can automatically rotate and move forward vertically according to the material properties and surface geometry. FEM simulations is also conducted to compare and validate the MPM simulation, showing that the proposed MPM wheel-soil model is effective in predicting the dynamic rotation problems.