冷却风扇叶片断裂分析

冷却风扇试验过程中叶片全部发生断裂,对断裂叶片进行外观检查、金相组织和显微硬度检测,对断口进行宏微观检查、能谱分析,综合分析叶片的断裂性质和原因。结果表明:冷却风扇叶片裂纹扩展阶段的典型特征为疲劳弧线及分布在疲劳弧线间的细密疲劳条带,发生了高低周复合疲劳断裂。叶片高低周复合疲劳断裂由较大离心力叠加振动应力的综合作用引起。建议优化叶片结构,提高叶片的承载能力,降低冷却风扇叶片振动应力,严格控制铸造质量,对叶片表面进行抗疲劳性能处理。

Fracture Analysis of Cooling Fan Blade

All blades of a cooling fan fractured during test. The failure mode and cause were analyzed by appearance observation, metallographic examination and hardness testing of the blades, as well as macro-and-micro observation of the fracture surface. The results show that the main characters in the fatigue crack propagation stage of the blades are beach marks and fine fatigue striations distributed at the zone between beach marks. Low-and-high cycle combined fatigue occurred to the blade. High centrifugal force combined with vibration stress caused low-and-high cycle combined fatigue of the blades. At last, improvement measures were proposed: improve structure of the blades in order to increase bearing capacity, decrease vibration stress of the blades, strictly control the casting quality, and carry out surface treatment of the blades in order to improve its fatigue resistance.