双粗糙面滑动摩擦过程应力与应变分析

建立了具有分形特征的二维双粗糙表面滑动接触模型,考虑材料的弹塑性变形及滑动过程中损伤失效,运用有限元方法动态探讨相嵌微凸体在滑动过程中应力与应变的变化情况.结果显示不同位置的等效塑性应变沿深度的变化规律不同,最大等效塑性应变量发生在摩擦次表层的某一深度处;随着塑性应变的增大,导致材料表层下微观裂纹的萌生,在外载荷持续作用下,表面一定深度处存在着一交错的剪切应力区,这一应力区阻止了裂纹沿深度方向扩展,但却促使了裂纹沿平行于摩擦表面方向的延伸裂纹扩展乃至发生断裂.

Stress and Strain Analysis in Sliding Contact with Two Fractal Surfaces

A 2-D sliding model of micro-scale was established between two rough surfaces exhibiting fractal behavior, and the stress and strain was discussed by using the finite element analysis. A pair of asperities was analyzed take into account elastic-plastic material properties with material failure. The transient stress/strain distribution of the rough solid was presented. The numerical results showed that the equivalent plastic strain versus different depth which at different locations showed different laws. Failure began beneath the surface at the region of highest plastic strain. A shear stress zone exited at a certain depth from the contact surface in the rear of the contact asperity. This shear stress zone on the one hand prevented the crack from extending along the depth direction, on the other hand, prompted the crack along an extension of the parallel to the direction of the friction surface crack growth and leads to final fracture.