Abstract The accuracy of discrete element model has great influence on the DEM simulations of lunar soil, especially on the soil-tool interaction simulations. In this paper, the mechanical property of lunar soil is classified into three categories and the particularity of shear strength is newly explained as higher internal friction angle and lower cohesion with respect to Earth soil, and the plasticity performance of lunar soil is emphasized. Two different constitutive laws are established as non-cohesion and apparent-cohesion ones, mainly distinguished by spring tension. Then four common kinds of addition methods of tension are introduced and compared in terms of limiting particles’ motion. The reason why spring tension is the most suitable tension model to simulate the cementing bond is analyzed from the perspective of soil aggregation theory and lunar soil chemical composition. An initial bonding state assumption is proposed, based on which a new alterable constitutive law is established to obtain a high-accuracy DEM model of lunar soil. Finally, the accuracy is verified by both shear strength indices and elastic-plastic behavior under both loose and dense conditions.

中文翻译：

---

一种月球土壤高精度DEM模型的可变本构律

摘要 离散元模型的精度对月球土壤DEM模拟，尤其是土-工具相互作用模拟有很大影响。本文将月土的力学性质分为三类，新解释了其抗剪强度的特殊性，即相对于地土具有较高的内摩擦角和较低的内聚力，并强调了月土的塑性性能。建立了两种不同的本构法则，即非内聚力和表观内聚力，主要区别在于弹簧张力。然后从限制粒子运动的角度介绍并比较了四种常用的加张力方法。从土壤团聚理论和月球土壤化学成分的角度分析了弹簧张力是模拟胶结粘结最合适的张力模型的原因。提出了初始键合状态假设，在此基础上建立了新的可变本构律，从而获得了高精度的月球土壤DEM模型。最后，通过松散和致密条件下的剪切强度指数和弹塑性行为来验证准确性。