散体单元法DEM的核心内容是运用所谓的中心差分法，实际上使用了迭代计算，在计算中确定合理的计算时步及其法向刚度是研究问题非常重要的方面，时步的选取与被研究颗粒的刚度、质量、阻尼，以及它们之间的匹配关系密切相关。目前，确定刚度的一般做法是实测，但实测只能对特定条件进行，且需要研究人员具有较丰富的经验，才能保证计算结果接近实际。本文通过质量—弹簧系统，对DEM计算过程进行理论与数值模拟讨论，给出确定计算时步和法向刚度的选取方法，对同类计算具有一定的参考意义。
The discrete element method (DEM), with its core of using the so-called central difference method, involves actually iterative calculations. During the DEM calculations, the determinations of a reasonable computation time step and the normal stiffness are very important. The determination of the time step is closely related to the stiffness, the mass and the damping of the granule in question, and to their matching relationship. To decide the stiffness is so far through actual measurements. However, it can be done only in some special conditions and it needs a wealth of experience for the simulation results to be close to the practical results. This paper, based on the theoretical consideration and numerical simulations of a mass-spring system, proposes optional ways to determine the calculation time step and the normal stiffness.
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