某汽车雨刮器上的刮杆接头在进行12 h的连续雪堵试验后发生断裂失效。为查明断裂原因, 对刮杆接头进行了宏观分析、断口分析、化学成分分析、硬度测试以及金相检验。结果表明: 该刮杆接头内侧R凸角的台阶处存在机械损伤缺陷, 裂纹源萌生于此机械损伤缺陷处, 加之R凸角台阶的应力集中效应, 故在连续雪堵试验时刮杆接头发生一次性大应力断裂。

A scraping rod joint of car wiper fractured after the test of continuous snow jam for 12 hours. Failure reasons of the scraping rod joint were analyzed through a set of tests of macroscopic examination, fracture analysis, chemical compositions analysis, hardness test and metallographic examination. The results show that the mechanical damage defects were found at the step of R salient which lied inside of the scraping rod joint, and the crack was initiated from the mechanical damage defects, along with the stress concentration of the step, so the one-time large stress fracture took place during the test of continuous snow jam.