ANCF Continuum-Based Soil Plasticity for Wheeled Vehicle Off-Road Mobility

Abstract

This technical brief describes the procedure and demonstrates the feasibility of integrating soil/tire models using the absolute nodal coordinate formulation (ANCF). The effects of both the soil plasticity and the tire elasticity are captured using ANCF finite elements (FEs). Capturing the tire/soil dynamic interaction is necessary for the construction of higher fidelity off-road vehicle models. ANCF finite elements, as will be demonstrated in this paper, can be effectively used for the modeling of tire and soil mechanics. In this investigation, the soil model is developed using ANCF hexahedral finite elements, while the tire model can be developed using different ANCF finite elements including beam, plate, or solid elements; ANCF plate elements are used in this investigation for demonstration purposes. The Drucker–Prager plastic material, which is used to model the behavior of the soil, is appropriate for the simulation of a number of types of soils and offers a good starting point for computational plasticity in terramechanics applications. Such higher fidelity simulations can be fruitfully applied toward the investigation of complex dynamic phenomena in terramechanics. The proposed ANCF/Drucker–Prager soil model is implemented in a multibody system (MBS) algorithm which allows for using the ANCF reference node (ANCF-RN) to apply linear connectivity conditions between ANCF finite elements and the rigid components of the vehicle. This new implementation is demonstrated using a tire of an off-road wheeled vehicle. The generality of the approach allows for the simulation of general vehicle maneuvers over unprepared terrain. Unlike other approaches that implement force or superelement models into an MBS simulation environment, in the approach proposed in this paper both the soil material and vehicle parameters can be altered independently. This allows for a greater degree of flexibility in the development of computational models for the evaluation of the off-road wheeled vehicle performance.