Ti-6Al-4V燕尾榫结构微动疲劳裂纹萌生及扩展行为研究

Study on the Initiation and Propagation of Fretting Fatigue Crack on the Ti-6Al-4V Alloy Dovetail Joint

针对Ti-6Al-4V钛合金燕尾榫连接结构在不同载荷下的微动疲劳现象,采用榫形微动疲劳试验进行研究,并对裂纹萌生扩展、微动磨损及断口进行分析。结果表明,微动疲劳使构件疲劳寿命显著降低约70%;疲劳载荷对微动裂纹扩展的影响比对裂纹萌生的影响更大;微动疲劳裂纹起始于接触面边缘,与接触表面约成45°角,裂纹扩展到60~150μm后转向与接触表面垂直;微动疲劳断口形貌表面在微动磨损区具有多个裂纹源点,但只有一个主裂纹形成。

Fretting fatigue tests were conducted on the Ti-6Al-4VTi alloy dovetail joint to investigate fretting cracks and wear under various load levels.The results indicate that the fatigue life is significantly reduced due to fretting of the dovetail joint.The fatigue loading has more influence on crack propagation than on crack initiation.The fretting cracks originate at the edge of the contact surface and orientate at 45°and stayed for 60~150μm,then propagate nearly perpendicular to the surface until fracture.The fracture surface shows that multiple cracking at contact surface but only one main crack dominated.