某公司生产的电动后桥壳在台架试验及路试过程中多次出现断裂,且断裂均发生于包壳与套管的环焊缝处。采用宏观观察、扫描电镜分析、化学成分分析、金相检验、焊缝熔深测试、有限元仿真分析等方法,对该电动后桥壳断裂的原因进行分析。结果表明:后桥壳包壳与套管的内径不一致,拼装后衬套台阶与包壳间存在间隙,导致包壳无法被完全焊透,在端面形成了尖角,尖角处产生的应力集中是导致后桥壳断裂的主要原因。建议优化设计方案,将包壳与套管间内错边的设计更改为外错边,取消衬套台阶并减小衬套开口,消除断面尖角,防止应力集中。

The electric rear axle housings proucluced by a company fractured many times during bench test and road test, and the fracture occurred at the circumferential weld between the cladding and the casing. The causes of the electric rear axle housing fracture were analyzed by macroscopic observation, scanning electron microscopy analysis, chemical composition analysis, metallographic examination, weld penetration inspection, finite element simulation analysis and other methods. The results show that the inner diameter of the cladding and casing of the rear axle housing was inconsistent. After assembly, there was a gap between the bushing step and the cladding, which caused the cladding to be unable to be fully welded, and sharp corners were formed on the end face. The stress concentration at the sharp corners was the main reason for the fracture of the rear axle housing. It was suggested to optimize the design scheme, changed the design of internal misalignment between the cladding and the casing to external misalignment, cancelled the bushing steps and reduced the bushing opening, eliminated the sharp corner of the section, and prevented stress concentration.