【作者】 崔金生；

【导师】 邓宗全；

【作者基本信息】 哈尔滨工业大学 ， 机械设计及理论， 2011， 硕士

【摘要】 月壤深层取样的目标之一是取回尽量保持原有层理信息的月壤样品。针对此目标,本文在比较传统土力学与离散元方法的基础上,利用离散元方法对内翻式软袋深层取样过程中模拟月壤的填充模型及特性进行仿真研究,并结合相关理论分析了主要结构参数和钻进规程参数对模拟月壤层理信息的具体影响方式,对月壤深层取样顺利实施、钻取机构的设计和研制以及深层取样规程的制定具有重要的意义。针对月壤的物理和力学特性,基于离散元方法软球模型,从细观角度建立了球形和非球形模拟月壤颗粒的接触力学模型和流动模型。基于二维离散元软件PFC2D,仿真分析了颗粒直径对模型精确度的影响,即粒径效应,并根据粒径效应提出了变颗粒直径建模方法。以此为基础,利用平移面模型在三维离散元软件EDEM中建立了内翻式软袋方式下模拟月壤深层取样过程的仿真模型。根据对月壤层理信息的要求,提出了层理信息的定量评价方法和评价指标。对取样管直压与内翻式软袋两种取样方式下的样品层理信息进行了对比分析。结果表明,内翻式软袋所取样品具有较好的层理信息。基于内翻式软袋方式下模拟月壤深层取样模型,仿真分析了取样管直径、软袋摩擦系数、进给速率、激振频率对模拟月壤深层取样过程中层理信息的具体影响方式。结果表明,只考虑模拟月壤的层理信息时,取样管直径和颗粒-软袋摩擦系数越大越好,进给速度越小越好,激振频率应该尽量远离模拟月壤固有频率。为钻取机构的设计和研制以及深层取样规程的制定提供了一定的参考依据。更多还原

【Abstract】 One of the purposes of the lunar soil deep-sampling mission is to obtain samples of lunar soil with original bedding information. Considering this purpose, this reseach compared traditional soil mechanics with discrete element method (DEM). Via DEM, the filling model and characteristic of lunar soil simulant in lunar soil deep-sampling with turnover flexible membrane was studied. Moreover, the impact of main structural parameters and drilling regulation parameters upon lunar soil simulant bedding information was analysed. This research has important significance for implementation of the lunar soil deep-sampling, design and development of drilling device, the formulation of the lunar soil deep-sampling regulation.Based on physical and mechanical properties of lunar soil and DEM elastic spheres model, contact mechanics model and flow model of spherical and non-spherical lunar soil simulant were established.With two-dimensional DEM software, PFC2D, simulation and analysis of the impact of particle diameter upon precision of model, the size effect was performed, grounded on which variable diameter modeling method was proposed. On this basis, lunar soil deep-sampling simulation model with turnover flexible membrane was established in three-dimensional DEM software, EDEM, with moving plane.According to the requirement of bedding information, the method and index of quantitative evaluation for it were proposed. Comparing the bedding information of direct penetrability sampling tube with that of turnover flexible membrane sampling tube shows that the turnover flexible membrane sample has better bedding information.Grounded on lunar soil deep-sampling simulation model with turnover flexible membrane, the impact of diameter of sample tube, friction coefficient of turnover flexible membrane, feed rate, excitation frequency upon bedding information in lunar soil deep-sampling were simulated and analyzed. The results show that the bigger sample diameter and the particle-membrane friction coefficient are or the smaller feed speed is, the better bedding information will be, and vibrant frequency should be kept away from the the natural frequency of lunar soil stimulant, which provide a reference for design and development of drilling device and the formulation of the lunar soil deep-sampling regulation.更多还原