航空发动机滑油箱支架断裂故障分析

Fracture Failure Analysis of Bracket in an Aeroengine Lubricating Oil Tank

针对某型航空发动机整机试车过程中多次发生的滑油箱支架断裂故障,对支架故障件进行了断口分析、装配状态结构位移测量、强度分析、振动应力分析,结果表明:由于滑油箱支架是双吊耳悬臂结构,在对滑油箱箍带施加拧紧力矩过程中,滑油箱支架双吊耳会产生明显的不协调变形,导致支架单侧吊耳由于偏载承受了较大的附加装配应力,随发动机工作时支架单侧吊耳综合应力增大,从而在吊耳应力集中位置发生高周疲劳断裂。通过将支架结构改为跨安装边的桥型连接结构,并用带球头螺母的双头螺杆将其与箍带进行连接,在滑油箱安装过程中保证支撑结构具有一定的长度和角度补偿能力,经强度分析、振动应力测量和发动机长久试车验证,滑油箱支架未再发生相同故障,表明改进方案可靠有效。

To deal with the repeated occurrences of fracture failure of the oil tank bracket during aeroengine tests,fracture analysis,structural displacement measurement,strength analysis,and vibration stress analysis of the failed component were carried out.The results show that because the oil tank bracket is a cantilever structure with double lifting lugs,the lifting lugs are unevenly deformed during the application of tightening torque on the oil tank strap,as a result,the lifting lug on one side of the bracket suffers larger additional assembly stress due to the uneven load,the combined stresses of the lifting lug on the one side of the bracket increases during engine tests,resulting in high-cycle fatigue fracture at the stress concentration position of the lifting lug.By changing the bracket structure to a bridge-type connection structure across the flange,and connecting it with the strap using a double-head bolt with a ball-joint nut,the support structure is guaranteed to have a certain length and angle compensation capacity during the installation of the oil tank.Through strength analysis,vibration stress measurement,and long-term engine tests,the oil tank bracket failure has not occurred again,indicating that the improvement is reliable and effective.