某型飞机肘形导管断裂故障分析与改进验证

针对某型飞机液压四通管路结构中肘形导管根部多次出现裂纹故障进行研究。根据裂纹位置和断口形貌,确定是由于过大弯曲应力和与平管嘴磨损综合作用下的快速疲劳断裂失效。通过模态分析,发现肘形导管的弯曲模态正好与发动机开车频段重叠,出现了以横向弯曲为主的共振振型,产生了较大弯曲应力,导致管壁磨损,与故障现象吻合。对此提出了3种改进方案:调整浮动卡箍位置、降低初始安装应力以及减小肘形导管长度。经过仿真分析和综合对比,得到了改进方向。基于应变测量方法,对肘形导管进行了机上发动机开车测试,通过试验数据验证了改进方向的可行性与有效性。

Fracture Failure Analysis and Improvement Verification of Elbow Tube in a Certain Type of Aircraft

The failure of the root of the elbow tube in the hydraulic tube system of a certain type of aircraft was studied.First,according to the location of the tube and the fracture morphology,the tub e’s rapid fatigue fracture failure was due to excessive bending stress and wearing of the flat nozzle.Then,through the modal analysis,it was found that the bending mode of the elbow tube coincided with the driving frequency band of the engine,a resonant mode which mainly for horizontal bending was expressed,resulting a large bending stress,which caused the wall to wear and matched with the fault.Thirdly,three improvements were proposed:adjusting the position of the floating clamp,reducing the initial installation stress and reducing the length of the elbow tube.The improved direction was determined after the simulation analysis and comprehensive comparison.Finally,based on the strain measurement method and engine test,the feasibility and validity of the improvement direction were verified by the test data.