月壤取芯动态过程复杂接触力学机理及实验研究

The third stage of China's lunar exploration project is the first attempt of unmanned task of lunar soil sample return to the earth. The existing ground simulation tests show that the failure mode would occur in the dynamic process of coring lunar soil, such as friction self-locking and jammed for soft bag, poor bedding protection performances and so on. Moreover, it is shown that how to reveal the formation mechanism of the failure modes is the bottleneck of experimental research. In order to reveal the contact mechanics mechanism of the failure modes, this project will systematically develop the dynamic simulation calculation theory for coring lunar soil. It involves the aspects of precise modeling method, the corresponding algorithm and analysis methods taking into account the uncertainty. Main subjects include: ALE-SPH adaptive coupling algorithm for the dynamic process of coring lunar soil is proposed, and the calculation of nonlinear large deformation problems such as buckling and fold will be made some breakthrough in process of soft bag turning inward. High precision calculation of soil feeding process in which the discrete flow coexists with the dense flow will be realized in simulations. An inverse method is developed to detect the black-box parameters in the dynamic process of coring lunar soil and the equivalent parameters of equivalent submodels. It will improve the modeling accuracy and reveal the mechanics mechanism of the self-locking and jammed phenomenon of soft bag. The interval analysis method of uncertainty is established to simulate and describe the bedding information of the lunar soil sample. It can directly reflect the evolution rule of the disturbance range between the system uncertainty inputs and the soil bedding characteristics. Finally, some corresponding experimental technology will be developed to validate the results of theoretical analysis. The theories and methods proposed in this project will promote the development of contact mechanics and solve the failure mechanism of black-box problems existing in experiments.

探月三期的核心任务是采样返回。地面模拟实验表明：月壤钻取采样器在取芯动态过程存在软袋摩擦自锁与卡死、壤芯分层特性保持性差等失效工况，也发现揭示失效工况的形成机理是实验研究的瓶颈。本项目将从精确建模方法、针对性的算法、考虑不确定性的分析方法等方面，系统地发展月壤取芯动态过程仿真计算理论，揭示失效工况的接触力学机理。具体包括：提出取芯动态过程ALE-SPH自适应耦合算法，突破软袋内翻过程屈曲、褶皱非线性大变形的计算难题，实现离散流与密实流共存的月壤进给过程的高精度计算；发展取芯动态过程黑箱参数反求方法，反演等效子模型的等效参数，提高建模精度，揭示软袋自锁与卡死现象的力学机理；建立壤芯层理特性保持性仿真的不确定性区间分析方法，揭示系统不确定性输入与壤芯层理特性扰动范围之间的演化规律；发展针对性的实验技术，验证理论分析结果。本项目的理论与方法将促进接触力学的发展，解决现有实验中的失效机理黑箱问题。

探月三期的核心任务是无人自主采样返回。地面模拟实验表明月壤钻取采样器在取芯动态过程存在一些失效工况，而如何揭示这些失效工况的形成机理及开展相关的力学分析是既具有重大工程应用价值也具有重要理论意义。本项目从精确建模方法、针对性的仿真计算、考虑不确定性的分析方法等方面，系统地发展月壤取芯动态过程计算分析理论，揭示失效工况的接触力学机理。针对性地发展测试技术和反求方法以获取取芯动态过程黑箱参数，反演等效子模型的等效参数；发展取芯过程理论、仿真与实验一体化分析方法，突破软袋内翻过程屈曲、褶皱非线性大变形的计算难题，实现取芯过程的高精度建模与计算；针对壤芯层理特性保持性分析难题，发展不确定性区间分析方法并结合理论、仿真与实验分析，提出样品扰动程度评价指标，揭示系统不确定性输入与壤芯层理特性扰动范围之间的演化规律。本项目发展的理论与方法解决了现有实验中的失效机理黑箱问题，直接应用到嫦娥五号钻取采样设计，为嫦娥五号圆满完成月壤钻取采集任务做出了贡献，获得航天部门专门颁发的感谢信。