颗粒介质物质点法与离散元法的多尺度建模

发布时间：2018-04-30 13:48

本文选题：颗粒介质 + 多尺度建模　；参考：《中国科学:物理学力学天文学》2017年07期

【摘要】：颗粒介质是由大量离散颗粒构成的无序材料,在工业生产与自然界中广泛存在.在外界作用下,颗粒材料可以类似固体保持稳定,也可类似流体发生流动,且类固体和类流体之间可以自然转化,目前人们难以采用统一的连续本构进行描述.本文提出了物质点法(Material Point Method,MPM)与离散元法(Discrete Element Method,DEM)的多尺度建模框架,亦即宏观尺度采用适用于大变形问题的MPM,颗粒尺度则采用DEM描述每个颗粒运动,每个物质点的力学性质由该点处若干颗粒构成的代表性体积元的力学性质计算得到,宏观尺度MPM所得变形梯度作为边界条件施加到体积元中,基于DEM计算得到域内的平均柯西应力,反馈到MPM计算,以此实现跨尺度研究.以沙堆倒塌作为算例,验证了MPM/DEM多尺度建模在描述颗粒复杂力学行为的有效性,并对倒塌过程中,宏观应变等信息与内在接触力链网络的关联进行了讨论.MPM/DEM多尺度建模没有引入唯象本构,且适用于大变形问题,为颗粒介质的多力学状态研究提供了新的思路.
[Abstract]:Granular media is a disordered material consisting of a large number of discrete particles, which exists widely in industrial production and nature. Under the action of the outside world, the granular materials can keep stable like solids or flow like fluids, and they can be transformed naturally between similar solids and fluid-like fluids. At present, it is difficult to use unified continuous constitutive equations to describe them. In this paper, a multi-scale modeling framework for material Point method (MPM) and discrete Element method (demm) is proposed. In other words, the macroscopic scale uses the MPMs suitable for large deformation problems, and the particle scale uses DEM to describe the motion of each particle. The mechanical properties of each material point are calculated by the mechanical properties of the representative volume element composed of a number of particles at the point. The deformation gradient obtained from the macroscopic scale MPM is applied to the volume element as a boundary condition. The average Cauchy stress in the domain is obtained based on the DEM calculation and fed back to the MPM calculation to achieve cross-scale research. Taking the sand pile collapse as an example, the effectiveness of MPM/DEM multi-scale modeling in describing the complex mechanical behavior of particles is verified. The relationship between macroscopic strain information and internal contact force chain network is discussed. The multi-scale modeling of MPM / Dem does not introduce phenomenological constitutive model, and it is suitable for large deformation problems, which provides a new idea for the study of multi-mechanical state of granular media.
【作者单位】：清华大学水沙科学与水利水电工程国家重点实验室;
【基金】：国家自然科学基金资助项目(编号:11272048,51239006,11572178
【分类号】：O347.7

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