某电动汽车在整车试验时出现导线断裂故障，通过宏观观察、微观观察、金相检验和能谱分析等方法对导线的断裂原因进行了分析。结果表明：电动汽车铜导线的断裂属于疲劳断裂；导线固定点设置不合理，线束可自由活动范围过大，使得整车振动试验时导线固定端受到过大的交变应力，导致运行一段时间后导线在固定点的插拔端子附近发生疲劳断裂；车辆继续运行中，导线断续接触，导致导线断口受到高温烧蚀，表面产生黑色覆盖物质，主要成分为铜的氧化物。

The wire fractured during the vehicle test of the electric vehicle. The causes of fracture on the wire were analyzed by macro observation, micro observation, metallographic examination and energy spectrum analysis. The results show that the fracture of copper wire of electric vehicle was fatigue fracture. The fixed point of the wire was set unreasonably and the free activities range was too large, resulting in excessive alternating stress on the fixed end of the wire during the vehicle vibration test. After running for a period of time, the wire fatigue fracture near the plug terminal of the fixed point. During the continuous operation of the vehicle, the conductor contacted intermittently, resulting in the high temperature ablation of the fracture of the conductor, and the black covering material was produced on the surface, which was mainly composed of copper oxide.