某航空卡箍连接结构中的燃油分配器主壳体及卡箍发生开裂。采用宏观观察、扫描电镜分析、金相检验及硬度测试等方法对卡箍连接结构开裂的原因进行分析。结果表明:燃油分配器主裂纹起源于安装边R角,呈多源、线源特征,为起始应力较大的双向弯曲疲劳开裂;卡箍发生了起始应力较大的疲劳开裂,裂纹起源于连接环内侧表面,呈多源、线源特征;燃油分配器与卡箍接触面受力不均是其发生早期疲劳开裂的主要原因,结合面挤压摩擦损伤也促进了疲劳裂纹的萌生。

The main shell of the fuel distributor and clamp in the aviation clamp connection structure cracked. The cracking causes of clamp connection structure were analyzed by macroscopic observation, scanning electron microscope analysis, metallographic examination and hardness test. The results show that the main crack of the fuel distributor originated from the R angle of the mounting edge and was characterized by multi-source and line source, which was a bidirectional bending fatigue crack with large initial stress. The clamp experienced fatigue cracking with large initial stress. The crack originated from the inner surface of the connecting ring, which was characterized by multi-source and line source. The uneven stress on the contact surface between the fuel distributor and the clamp was the main reason for its early fatigue fracture and the extrusion friction damage of the joint surface also promoted the initiation of fatigue cracks.