微凸体碰撞对接触应力应变的影响

基于有限元法建立了单对半球状微凸体的接触、碰撞模型,研究了碰撞对微凸体在完全弹性、弹塑性和完全塑性三种接触状态下的Mises应力分布和等效塑性应变(PEEQ)的影响.结果表明:接触变形状态不同时,微凸体的Mises应力分布在碰撞过程具有不同的变化过程,但碰撞结束后,Mises应力值都降低,仅在完全塑性接触时,个别节点的Mises应力峰值大于屈服极限.碰撞使微凸体的等效塑性应变迅速增加到峰值,并保持到碰撞结束,与接触变形状态无关.完全弹性、弹塑性接触状态和完全塑性接触状态下,微凸体等效塑性应变的峰值分别位于接触中心区域和应变峰值环,这意味着裂纹可能产生的部位也不同.

Influence of Asperity Collision on Contact Stress and Strain

The contact model and collision model of hemisphere asperity pair were established by finite element method, and the influence of asperity collision on Mises stress and equivalent plastic strain (PEEQ) were analyzed taking into account fully elastic contact, elastoplastic contact and fully plastic contact. The numerical results show that the changing processes of Mises stress distributions in the asperities depended on contact status. The Mises stress decreased and was no longer greater than yield limit after the collision in addition to several nodes in the fully plastic contact status. The PEEQ of the asperities increased rapidly to their maximum and were constant till the end of the collision regardless of the contact status of the asperities. The maximum of PEEQ of the asperities were in different location, and this result implies there were different locations of crack initiation in different contact status.