航空发动机燃油总管支架断裂故障分析

Investigation on fuel manifold bracket fracture failure for an aero-engine

某型航空发动机在整机试车过程中多次发生燃油总管支架断裂故障,断口分析表明为高周疲劳断裂。利用有限元方法对该燃油总管系模态进行计算分析,结果表明燃油总管系有多阶固有频率落在发动机共振频率范围内,严重不满足设计要求,存在极大的共振可能性,并通过动应力测试予以了验证。为解决共振问题,采取增加燃油总管支架刚度和支架数量的方法,将燃油总管的最低共振频率调在发动机共振频率范围之外。经后续试验验证,燃油总管系未出现相同故障,支架断裂故障得以排除。

Fracture failure of manifold bracket occurred several times in an aero-engine test run process. Fracture analysis demonstrated that the bracket failure due to high-cycle fatigue. Finite element method was used in computation modal analysis of the fuel manifold system, which revealed that natural frequency of several orders have been within the range of engine resonance frequency and it was likely to resonate. Dynamic stress measurement verified this threat. The stiffness and number of brackets have been increased in order to raise the lowest natural frequency beyond the resonance frequency range. And the following tests verified that the bracket fracture failure was cleared in this way.