曲轴再制造毛坯连杆轴颈表面损伤对剩余疲劳寿命的影响*

为研究曲轴连杆轴颈表面损伤与曲轴再制造毛坯剩余疲劳寿命的相关性,基于有限元仿真计算获得的曲轴过渡圆角应力分布结果,选取含表面自然缺陷和人工预制缺陷的废旧曲轴,在谐振式弯曲疲劳试验台上进行曲轴弯曲疲劳试验。采用金相显微镜和扫描电镜观察疲劳断口处的组织和形貌,分析讨论表面缺陷对剩余疲劳寿命的影响。研究结果表明:废旧曲轴剩余疲劳寿命对于缺陷位置的敏感程度高于缺陷尺寸,连杆轴颈表面氮化层的剥落造成废旧曲轴剩余疲劳寿命显著降低。

Influence of Surface Defect of Crankpin for Crankshaft Remanufacturing Core

In order to investigate the correlation between surface damage of crankpin and remaining fatigue life of the crankshaft remanufacturing core, the result of stress distribution on crankpin fillets was obtained based on calculation of finite element method and wasted crankshafts with natural surface defect. Precut surface defects were selected to conduct bending fatigue test on the resonant fatigue test rig. Microstructure and morphology of fatigue fracture were observed by metallographic microscope and scanning electron microscope. The influence of surface defects for remaining fatigue life was analyzed. The results showed that detect position is more sensitive to remaining fatigue life than defect size of the wasted crankshaft and remaining fatigue life of the wasted crankshaft decrease significantly due to peeling of the surface nitrided layer.