可用于塑性材料的离散单元滞回力矩滚动阻力模型

Hysteresis Torque Rolling Resistance Model Based on Discrete Element for Plastic Materials

针对现有弹簧阻尼滚动阻力模型无法准确表达塑性材料形变的受力变化的问题,提出一种用于塑性颗粒材料的新型离散单元滚动阻力模型——滞回力矩滚动阻力模型.以粒子材料弹塑性形变理论为基础,将粒子滚动过程中离散单元的滚动接触摩擦力矩描述为滞回项和阻尼项,滞回项表示其接触中心点前后处于受力不平衡的塑性变形状态,阻尼项表示粒子表面的摩擦.通过沙堆试验对此离散单元滚动接触模型进行验证,实现了粒子接触中心点前后受力不平衡塑性变形状态的更高精度表达.从粒子接触微观过程而言,所提出的模型更符合材料塑性变形力学机理,能更好地应用于塑性颗粒材料的仿真研究.

As the original spring-damper rolling resistance model cannot accurately express the change of the deformation of plastic materials,this paper presents a new rolling resistance model based on discrete element for plastic materials,namely the hysteresis torque rolling resistance model.In this model,based on the elasto-plastic deformation theory of particle materials,the rolling resistance torque of the discrete element particles is described as a hysteresis term and a damping term.The hysteresis term expresses the force imbalance caused by the state that the front half of the contact portion is in the deformation process and the latter half in the recovery process,while the damping term expresses the friction on particle surface.The presented rolling contact model is then verified by a particles pile test and achieves a more accurate expression of the unbalanced plastic deformation state on both sides of the particle contact center.From the viewpoint of microscopic process of particle contact,the proposed model is more consistent with material s elastic-plastic deformation mechanism and can be widely used to simulate plastic materials.