Hertz contact model was used to deal with normal impact force, and Hertz tangential contact model and Coulomb friction model were used to deal with static tangential impact force and slip frictional force, respectively.

• 用Hertz接触模型处理法向撞击力,分别用Hertz切向接触模型和Coulomb摩擦力模型处理粘滞状态和滑动状态的摩擦力。