离散元聚苯乙烯颗粒细观参数辨识

Mesoscopic identification of polystyrene particles based on discrete element

真空担架由聚苯乙烯(EPS)颗粒和聚氯乙烯(PVC)软膜组成,在使用离散元法仿真研究担架真空变形机理时,颗粒的细观参数对仿真精确性至关重要。该文基于Hertz-Mindlin接触模型,利用实验结合仿真模拟的方法对颗粒离散元参数进行辨识。通过斜面滑移实验,碰撞弹跳实验测定EPS颗粒与PVC软膜之间的静摩擦因数和恢复系数,分子动力学仿真模拟方法测定出颗粒与颗粒的滚动摩擦系数,得到结果分别为:0.885、0.506、0.02。以休止角为响应值,根据最陡爬坡实验确定其余参数最佳范围,结合Box-Behnken实验建立休止角与参数的二阶回归模型,得出颗粒与颗粒的静摩擦因数为0.40,EPS颗粒与PVC软膜的滚动摩擦系数为0.45,EPS颗粒与颗粒的碰撞恢复系数为0.43。最后用测定的参数进行侧面崩塌仿真模拟,与崩塌实验休止角误差1.9%,表明测定后的EPS细观参数可用于离散元仿真。

The vacuum stretcher is composed of polystyrene(EPS)particles and PVC(PVC)soft film.When using discrete element method to study the vacuum deformation mechanism of stretcher,the microscopic parameters of particles are very important to the accuracy of simulation.In this paper,the Hertz-Mindlin contact model is used to identify the discrete element parameters of particles.The static friction factor and recovery coefficient between EPS particles and PVC soft film were measured by slant slip experiment,and the rolling friction coefficient between particles and PVC soft film was determined by molecular dynamics simulation,and the results were 0.506,0.885 and 0.02.The resting Angle was taken as the response value,the optimal range of other parameters was determined according to the steepest climb experiment,and the second-order regression model of resting Angle and parameters was established in combination with box-Behnken experiment.It was obtained that the static friction factor between particles was 0.40,the rolling friction coefficient between EPS particles and PVC soft film was 0.45,and the collision recovery coefficient between EPS particles was 0.43.Finally,the measured parameters were used for side collapse simulation,and the repose Angle error between the measured parameters and the real test was 1.9%,indicating that the measured EPS microscopic parameters could be used for discrete element simulation.