某型直升机尾桨断裂故障分析

明确某型直升机尾桨断裂故障原因，对于该型机的使用、维护有现实意义，对于新机型的安全性提升有借鉴意义。首先通过故障树分析法对某型直升机尾桨叶断裂故障进行分析，得到底事件分析结果；然后开展宏、微观断口分析；最后对柔性梁断口损伤演化开展仿真分析。结果表明：桨叶断裂性质为低应力高周双向弯曲疲劳断裂，当柔性梁纤维压缩方向强度性能值小于700 MPa 时，断口的形式与故障尾桨柔性梁断口类型相似；大载荷状态尾桨会产生较大的振动，振动的增加加剧了尾桨的载荷，导致尾桨柔性梁根部载荷增加，超出柔性梁设计承载能力，桨叶柔性梁根部疲劳断裂。

Fracture fault analysis of tail rotor on a helicopter

Aiming at the fault of a helicopter tail rotor blade fracture, the fault cause analysis is carried out by fault tree analysis method, and the bottom event analysis results are obtained. By carrying out failure analysis of the blade, the results of macro and micro fractographic analysis shows that the fracture property of the blade is low-stress and high-cycle bidirectional bending fatigue fracture. The simulation analysis of the fractographic damage evolution of flexible beam shows that when the strength value of the fiber compression direction of the flexible beam is less than 700MPa, the fractographic type is similar to that of the faulty tail rotor flexible beam. Comprehensive analysis shows that the tail rotor will produce large vibration under large fatigue load condition, and the increase of vibration intensifies the load of the tail rotor, leading to the increase of load at the root of the flexible beam, exceeding the designed bearing capacity of the flexible beam, then fatigue fracture at the root of the flexible beam of the blade.