变重力场中散体颗粒堆的安息角及接触力分布

为研究重力与散体颗粒堆安息角的关系,针对颗粒系统的随机性和离散性特点,通过三维离散单元法建立颗粒的运动模型,对颗粒在不同重力场中的堆积过程进行了模拟,得出了颗粒堆的安息角及接触力概率分布.结果表明:颗粒堆内接触力构成的力链呈非规则网络状,其中,接触力近似对数正态分布,约65%接触力低于平均值;接触点中约70%处于临界滑移,其余接触点切向力与法向力的比值为均匀分布;不同重力场中颗粒堆接触力的分布规律具有相似性,即接触力相对重力无量纲化之后,其分布函数高度相符;颗粒堆的微观结构具有随机性差异,但是安息角不受重力大小的影响.

Angle of repose and contact-force distribution in granular pile under variable g

Taking the discontinuity and random character of granular system into account, a kinematic model of particles was established by three-dimensional discrete element method in order to investigate the relationship between angle of repose and gravity. Accumulation process of granular pile was simulated using the model under variable gravity. The angle of repose and probabilistic distribution of contact forces were obtained in the model. Results show that the force-chain formed from contact forces within particle pile has the characteristics of structure of irregular mesh. Contact forces within particle pile are approximately log-normal distributed and there are about 65% of contacts carrying a force lower than the mean. Moreover, there are about 70% of contacts whose friction force are fully mobilized and the ratio of tangential force to normal force among the rest of contacts is uniformly distributed. The distributions of contact force of granular piles in different gravity field have similar properties. The contact forces, which are normalized with respect to particle's gravity, of piles with variable gravity have nearly the same distribution. The angle of repose is not affected by the gravity, though granular pile has a randomness property of microscopic structure.