聚四氟乙烯软管气蚀引起疲劳损伤的形貌分析

飞机液压系统用聚四氟乙烯软管在使用中先后发生10余起软管内壁穿孔造成的渗漏故障.利用视频显微镜、扫描电镜等对故障软管进行宏观及微观形貌分析.结果表明:故障软管具有相同的失效特征及模式,属于气蚀引起的疲劳损伤;结合软管工作环境,探讨软管气蚀疲劳损伤的机理,总结气蚀引起疲劳损伤的形貌特征,即宏观上损伤区为蜂窝状孔洞形貌,微...

Morphology Analysis on Fatigue Failure of PTFE Pipe Caused by Cavitation Erosion

A dozen of polytetrafluoroethylene (PTFE) pipe leakage occurred on hydraulic system of a certain aircraft. Three-dimension microscope and SEM were used to analyzed macro and micro morphology of faulty PTFE pipe. The results showed that these PTFE pipes hade same failure characteristics and failure mode, which is named fatigue failure caused by cavitation erosion. The paper analyzed working condition of PTFE pipe, investigated failure mechanism of cavitation erosion, and concluded fractal characteristics of fatigue failure caused by cavitation erosion. Characteristic features of such failures included: 1) feature of damage zone were honeycomb-like caves macroscopically, 2) caves consisted of small fatigue zones microscopically, 3) cracks that propagate first at surface or subsurface and then parallel to the surface of pipe, and 4) fatigue striations on the fracture surfaces. Fatigue failure caused cavitation erosion of PTFE pipes could be described by shock wave mechanism.