抄録
The influence of the strain rate sensitivity of the yield stress on multiple impact of three identical spheres were examined by FEM analysis in this study. Firstly the influence on colliding behavior were investigated. Then, the influence on macro-characteristics such as maximum contact force, maximum deformation, coefficient of restitution were investigated in detail. The main results obtained from this study were listed below. (1)The post impact speed of ball 2 (central ball) receives almost none of influence of the strain rate sensitivity of the yield stress. However, the post impact speed of ball 1 (collision ball) is overestimated and those of ball 3 (ball of another side) is underestimated if the strain rate sensitivity of the yield stress is ignored. In addition, a time delay was seen in the speed change during collision in the case without strain rate sensitivity. (2)The maximum deformation and impact duration are overestimated, and maximum contact force and contact pressure are underestimated, if the strain rate sensitivity of the yield stress is ignored. Further, the influences increase with increase in impact speed. (3)The contact stiffness and coefficient of restitution are underestimated in the case without strain rate sensitivity of the yield stress, and the influence become greater with impact speed in e11 than e12. In addition, e11 showed a negative value (re-collision) in the case with strain rate sensitivity when impact speed increased, while e12 was positive in the case without strain rate sensitivity. The influence of the strain rate sensitivity on the contact stiffness and the re-collision in detail in future.
