磨损加疲劳载荷下的协同疲劳行为

自行研制的摩擦磨损装置与轴向疲劳试验机相互配合,实现GDL-1钢试样在疲劳应力(240~280 MPa)及接触载荷(30 N)作用下摩擦磨损疲劳试验.通过对磨损层厚度的分析,研究试样承受摩擦磨损载荷及拉压疲劳载荷双重作用下的疲劳寿命变化,用SEM扫描电镜观察分析次表层内疲劳裂纹扩展的演变过程,并采用Hertz线弹性理论和Smith接触理论计算分析摩擦表面以下切应力值.结果表明:在磨损疲劳载荷作用下,形变层的流变作用将显著影响疲劳小裂纹扩展方向,渐趋于切应力方向,从而提高试样疲劳寿命.在此基础上,建立了在摩擦磨损疲劳载荷下疲劳裂纹扩展模型.此外,计算可知在距表层深度0.03 mm处切应力最大,0.18 mm以内材料产生塑性变形,导致形变层的形成.

Collaborative Fatigue Behavior under Wear and Fatigue Co-loads

The wear and fatigue tests of GDL-1 steels specimens were carried out by using a self-developed wear and fatigue equipment under different levels of strain ranging from 240 to 280 MPa with contact loads of 30 N. Through analyzing wear volume of specimens,the effect of wear and fatigue co-loads on fatigue life of specimens were studied. The propagation mechanism of micro-cracks on subsurface were observed by scanning electron microscopy,and the shear stress values below the contact surface were calculated by using Hertz Linear Elastic Theory and Smith Contact Theory. Experimental results show that under the wear and fatigue Co-loads,rheological effect of deformation layer made the fatigue micro-cracks expand gradually parallel with sheer stress direction,and contribute to improve fatigue life. Under this condition,a model of fatigue cracks propagation under wear and fatigue co-loads was proposed preliminarily. Calculation results show that the x_z in depth of 0.03 mm was the maximum and the specimens below depth of 0.18 mm may be caused plastic deformation to form the deformation layer.