Abstract In Discrete Element Method (DEM), the stiffness of particles is often reduced from the real material property to increase the time step and decrease the calculation cost. Although this approach is widely accepted for dry and relatively coarse particles where only contact force is dominant, it is recently reported that the powder behaviour changes drastically with reducing the particle stiffness when cohesion forces are exerted on the particles [1] , [2] . The present study generalises this problem to any type of attraction forces and provides a solution, which is named as the Reduced Particle Stiffness (RPS) scaling. The RPS scaling for both linear and non-linear contact models are developed based on the dimensionless equation of motion where additional attraction forces such as liquid bridge, cohesion and electrostatic forces are exerted on particles. It is proven that, using the RPS scaling, particles with reduced stiffness show similar sticking/rebound behaviour and the bulk velocity as those of the original (stiff) particles.

中文翻译：

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具有吸引力的 DEM 使用降低的粒子刚度

摘要 在离散元法(DEM)中，为了增加时间步长，降低计算成本，往往从实际材料属性中降低粒子的刚度。尽管这种方法被广泛用于干燥和相对粗糙的颗粒，其中只有接触力占主导地位，但最近有报道称，当内聚力施加在颗粒上时，粉末行为会随着颗粒刚度的降低而发生剧烈变化 [1]、[2]。本研究将此问题推广到任何类型的吸引力，并提供了一种解决方案，称为降低粒子刚度 (RPS) 缩放。线性和非线性接触模型的 RPS 缩放是基于无量纲运动方程开发的，其中额外的吸引力，如液桥，内聚力和静电力施加在粒子上。事实证明，使用 RPS 缩放，刚度降低的颗粒表现出与原始（刚性）颗粒相似的粘附/回弹行为和体积速度。