# Modeling of the interaction of rigid wheels with dry granular media

## TL;DR

This paper compares Resistive Force Theory and continuum plasticity via Material Point Method for modeling wheel interactions with dry granular media, showing RFT's efficiency and continuum modeling's detailed insights.

## Contribution

It demonstrates the effectiveness of RFT and continuum plasticity models in simulating wheel-granular media interactions, highlighting their advantages over traditional methods.

## Key findings

- RFT reliably predicts wheel forces with high accuracy.
- Continuum modeling captures detailed stress and flow fields.
- RFT outperforms traditional terramechanics in certain scenarios.

## Abstract

We analyze the capabilities of various recently developed techniques, namely Resistive Force Theory (RFT) and continuum plasticity implemented with the Material Point Method (MPM), in capturing dynamics of wheel--dry granular media interactions. We compare results to more conventionally accepted methods of modeling wheel locomotion. While RFT is an empirical force model for arbitrarily-shaped bodies moving through granular media, MPM-based continuum modeling allows the simulation of full granular flow and stress fields. RFT allows for rapid evaluation of interaction forces on arbitrary shaped intruders based on a local surface stress formulation depending on depth, orientation, and movement of surface elements. We perform forced-slip experiments for three different wheel types and three different granular materials, and results are compared with RFT, continuum modeling, and a traditional terramechanics semi-empirical method. Results show that for the range of inputs considered, RFT can be reliably used to predict rigid wheel granular media interactions with accuracy exceeding that of traditional terramechanics methodology in several circumstances. Results also indicate that plasticity-based continuum modeling provides an accurate tool for wheel-soil interaction while providing more information to study the physical processes giving rise to resistive stresses in granular media.