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某型轮式装载机轮边减速支撑轴出现断裂,分析确认为疲劳失效。裂纹起源于花键根部,纵向扩展到一定长度和深度后,产生新的横向及45°扩展裂纹,最终导致支撑轴断裂。对支撑轴的结构和工作受力分析表明,使用过程中花键根部存在应力集中区域。经检测发现失效件调质质量不合格,强度低于设计要求;同时花键加工刀痕粗大成为疲劳裂纹源点,致使支撑轴使用疲劳强度不足,造成疲劳失效。利用ANSYS对支撑轴工作状况进行有限元模拟分析,模拟结果显示支撑轴花键根部存在高应力集中区域,与实际断裂部位一致。综合分析结果,认定热处理质量不合格,花键加工表面缺陷是导致支撑轴强度不足,造成疲劳断裂失效的根本原因。
A type of wheel loader wheel rim deceleration support shaft rupture, analysis confirmed fatigue failure. Cracks originated in the spline root, the longitudinal expansion to a certain length and depth, resulting in a new horizontal and 45 ° extended crack, eventually leading to fracture of the support shaft. The analysis of the structure and work force of the support shaft shows that there is stress concentration area in the spline root during use. After testing, it is found that the quality of the quenched and tempered failed parts is unqualified and the strength is lower than the design requirement. At the same time, the spline machining marks become the source of the fatigue crack, resulting in insufficient fatigue strength of the supporting shaft, resulting in fatigue failure. The working condition of the supporting shaft was analyzed by finite element method with ANSYS. The simulation results showed that there was high stress concentration area in the root of the supporting shaft, which was consistent with the actual fracture site. According to the results of comprehensive analysis, it is concluded that the quality of heat treatment is unqualified. The spline machining surface defects are the root cause of the insufficient strength of the support shaft and the failure of fatigue fracture.