弹塑性自黏结颗粒聚合体碰撞破损的离散元法模拟研究

Discrete element modelling of impact attritions of agglomerates of autoadhesive elastoplastic particles

利用颗粒离散元方法,并结合接触力学理论,对自黏连、弹塑性颗粒聚合体碰撞破损的细观力学机理进行了模拟研究。在颗粒间塑性变形存在的条件下,研究了颗粒物碰撞损伤。将弹性颗粒体碰撞与弹塑性颗粒体碰撞结果作了比较。结果表明:其他同等条件下,与弹性颗粒聚合体相比,弹塑性颗粒聚合体的损伤模式多为衰变或解体,而非断裂,其原由可以归结为塑性变形引起的额外能量损耗;其他同等条件下,与弹性颗粒聚合体比较而言,弹塑性颗粒聚合体碰撞加载阶段平板撞击力波动振幅较小,加载时间较长,撞击力峰值较大,且峰值出现的时间较晚,而损伤率却较大,其原因可以归结为颗粒间塑性变形对动能损耗、局部结构变化、内部力传播的影响。

In this paper, discrete element modelling of agglomerate impact has been conducted by adopting the theory of contact mechanics for elastoplastic auto-adhesive particles. Results show that, under the same conditions other than the predefined yield pressure, the elasto-plastic agglomerate tends to disintegrate during impact in contrast to the elastic agglomerate which has fractured in terms of breakage pattern. Due to the presence of plastic deformation and additional kinetic energy loss, the elastoplastic agglomerate during impact needs longer loading period than the elastic agglomerate, and generates larger peak wall force and greater internal damage. It was also observed that the amplitude of wall forces during loading is relatively smaller than the corresponding elastic agglomerate. However, during unloading, the remaining kinetic energy become less.