FEA Setup Guide for Agricultural Tire–Soil Interaction (ANSYS APDL & Abaqus)

Agricultural tire–soil interaction is governed by highly nonlinear, path-dependent behavior: tires exhibit large-strain hyperelasticity and viscoelastic hysteresis, while soils respond as pressure-sensitive, dilatant, strain-rate-dependent materials exhibiting plastic yielding, creep, and moisture-dependent strength degradation. Accurate simulation requires coupling these behaviors via robust contact formulations—such as penalty-based or augmented Lagrangian methods—that resolve evolving contact areas, frictional slip, and normal pressure redistribution under dynamic loading (e.g., rolling, braking, turning). In ANSYS APDL, this involves defining element types (SOLID186 for soil, HYPER56 for rubber), implementing user-subroutines (USERMAT for advanced soil models like Modified Cam-Clay or Drucker–Prager with cap), and leveraging *CONTACT_PAIR with adaptive stabilization; in Abaqus, it relies on surface-to-surface contact with friction (Coulomb + pressure-overclosure), coupled temperature-displacement elements (CAX8RT) for thermomechanical effects, and user-defined material subroutines (UMAT/VUMAT) for rate-dependent soil response. Validation is critical and typically includes comparison against plate sinkage tests, 3D pressure mapping (e.g., Tekscan), and field-measured contact length/width—requiring careful calibration of soil cohesion, friction angle, bulk modulus, and tire inflation pressure. Furthermore, mesh strategy must balance accuracy and cost: local mesh refinement beneath the contact patch, hourglass control for reduced-integration soil elements, and tie constraints or MPCs to enforce rim–tire bonding without artificial stiffness.