Abstract Aiming to solve the computational cost problem in the discrete element simulation for lunar soil drilling sampling, an equivalent boundary method was proposed. A high-accuracy DEM model of lunar soil was established firstly. As the novel alterable constitutive law, the accuracy of the model was verified to meet the performance of real lunar soil very much both in shear strength indices and elastic–plastic behavior. A common drill bit in the geological exploration field for sampling soil was chosen as the simulation object. In preanalysis, it was known that with the increase of drilling depth, the stress concentration area was always near the drill bit, while the affected area of the lunar soil was a cylindrical area around the drill pipe, which extended towards the drilling direction instead of extending around it. Then a big boundary drilling simulation scene was established to investigate the flow direction of lunar soil particles. The motion law of particles and the velocity field information were obtained, and a U-shape chain was described around the drill bit. Finally an equivalent boundary was set near the U-shaped chain, and the size was determined by comparing the soil stress in the fierce collision zone and around the reference boundary. This method could be a reference for other lunar soil drilling researches with other drills of different sizes.

中文翻译：

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DEM模拟月球土壤钻探等效边界模型

摘要 针对月球土壤钻孔采样离散元模拟计算成本问题，提出了一种等效边界法。首次建立了高精度的月球土壤DEM模型。作为新的可变本构律，验证了模型的准确性，在剪切强度指标和弹塑性行为方面都非常满足真实月球土壤的性能。选取地质勘探领域常用的一种土样取样钻头作为模拟对象。经预分析可知，随着钻孔深度的增加，应力集中区始终位于钻头附近，而月壤的影响区域是钻杆周围的圆柱形区域，向钻孔方向延伸而不是围绕它延伸。然后建立大边界钻探模拟场景，研究月球土壤颗粒的流动方向。获得了粒子的运动规律和速度场信息，并在钻头周围描述了一个U形链。最后在U形链附近设置等效边界，通过比较剧烈碰撞区和参考边界周围的土壤应力来确定其大小。该方法可为其他不同尺寸钻头的月壤钻探研究提供参考。大小是通过比较剧烈碰撞区和参考边界附近的土壤应力来确定的。该方法可为其他不同尺寸钻头的月壤钻探研究提供参考。大小是通过比较剧烈碰撞区和参考边界附近的土壤应力来确定的。该方法可为其他不同尺寸钻头的月壤钻探研究提供参考。