滚珠式操纵软轴中滚珠接触应力分析

Study on Contact Stress of Balls in Flexball

针对芯部滑杆与滚珠之间的多接触问题,基于冲击函数法,应用ADAMS软件进行动力学仿真分析,获得各芯部滑杆与滚珠之间的接触力。选取芯部滑杆受拉时,受接触力最大的dw8号滚珠作为研究对象,在ABAQUS环境下建立接触模型,求解接触应力参数。主要结论如下:1)推拉芯部滑杆时,芯部滑杆上下表面受交变接触应力,且最大应力幅值比滚珠大,使其较滚珠更易出现接触疲劳;2)Mises等效应力由芯部滑杆内部向外先增大后减小,而最大值出现在接触面以下一定距离,故疲劳裂纹多由芯部滑杆内部产生,而逐渐向其表面扩展。

In order to acquire the contact force between balls and central rail, the ADAMS software was utilized to perform the dynamic simulation for the multi-contact problem of central rail and balls based on impact function method. The dw8 ball which experienced the maximum contact force was chosen as the research model for the case that the central rail was subjected to tension. Contact stress parameters were obtained with a contact model established in ABAQUS software. It can be concluded that： 1 ） When a central rail is being pushed or pulled, the alternative contact stress will exist on both upper and lower surfaces of the central rail and the stress amplitude is larger than that on the ball, which makes the surface of central rails be prone to contact fatigue damage; 2） The amplitude of Von Mises stress is firstly increased and then decreased from the inner to the outer, and the maximum amplitude occurrs slightly below the contact surface, which explains the reason why the fatigue cracks usually forms inside of the contact body and slowly extends to the surface. The simulation test and conclusions provide useful results for future study of the durability design of flexballs.