Abstract The discrete element method (DEM) is widely seen as one of the more accurate, albeit more computationally demanding approaches for terramechanics modelling. Part of its appeal is its explicit consideration of gravity in the formulation, making it easily applicable to the study of soil in reduced gravity environments. The parallel particles (P2) approach to terramechanics modelling is an alternate approach to traditional DEM that is computationally more efficient at the cost of some assumptions. Thus far, this method has mostly been applied to soil excavation maneuvers. The goal of this work is to implement and validate the P2 approach on a single wheel driving over soil in order to evaluate the applicability of the method to the study of wheel-soil interaction. In particular, the work studies how well the method captures the effect of gravity on wheel-soil behaviour. This was done by building a model and first tuning numerical simulation parameters to determine the critical simulation frequency required for stable simulation behaviour and then tuning the physical simulation parameters to obtain physically accurate results. The former were tuned via the convergence of particle settling energy plots for various frequencies. The latter were tuned via comparison to drawbar pull and wheel sinkage data collected from experiments carried out on a single wheel testbed with a martian soil simulant in a reduced gravity environment. Sensitivity of the simulation to model parameters was also analyzed. Simulations produced promising data when compared to experiments as far as predicting experimentally observable trends in drawbar pull and sinkage, but also showed limitations in predicting the exact numerical values of the measured forces.

中文翻译：

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车轮-土壤相互作用的离散元建模和重力影响分析

摘要 离散元法 (DEM) 被广泛认为是一种更准确但计算量更高的地形力学建模方法。它的部分吸引力在于它在公式中明确考虑了重力，使其很容易适用于低重力环境中的土壤研究。用于地形力学建模的平行粒子 (P2) 方法是传统 DEM 的替代方法，其计算效率更高，但需要一些假设。迄今为止，该方法主要应用于土壤开挖作业。这项工作的目标是在单轮驱动土壤上实施和验证 P2 方法，以评估该方法在研究车轮-土壤相互作用中的适用性。特别是，这项工作研究了该方法如何很好地捕捉重力对车轮土壤行为的影响。这是通过建立模型并首先调整数值模拟参数以确定稳定模拟行为所需的临界模拟频率，然后调整物理模拟参数以获得物理上准确的结果来完成的。前者通过不同频率的粒子沉降能量图的收敛进行调整。后者通过与在重力减小的火星土壤模拟物的单轮试验台上进行的实验收集的牵引杆拉力和车轮下沉数据的比较进行调整。还分析了模拟对模型参数的敏感性。