发动机燃油供油导管开裂分析

在进行地面检查时发现发动机燃油供油导管焊缝处开裂漏油，结合宏观观察、断口分析、化学分析、金相检查以及有限元模拟等，对其开裂原因进行分析。结果表明:未被卡箍有效固定的供油导管受较大振动载荷作用，在较粗糙的接嘴焊缝根部应力集中处萌生疲劳裂纹，进而疲劳扩展，与内表面烧穿区边缘的焊接微裂缝贯通，导致导管焊缝漏油。焊接时2次收弧的叠加导致导管局部焊穿，焊道表面状态恶化，且材料综合性能下降，促进导管发生疲劳开裂。通过调整导管与卡箍的配合方式、降低线能量等方法，可以有效控制此类故障的发生。

Crack Analysis of Supplying Fuel Pipe for Aircraft Engine

When an airplane was inspected that an inspector found the fuel leaked off from the supplying fuel pipe for engine. It was caused by the welding joint crack. The crack cause of the pipe was analyzed by macro analysis, fracture surface analysis, chemical analysis, metallographic examination. The results show that assembly is not precise between the supplying fuel pipe and the clamp band. The crack occurred in the rough welding root where stress concentration existed. The character of crack is fatigue. And the fatigue crack doesn’t penetrate the all thickness of the pipe, but it meets the welding micro-crack in the inner surface of the burn-through area. All these factors caused the pipe leaked off finally. Two welding craters isn’t good to the combination property of the part.