飞行器径向连接螺栓振动断裂分析

应用有限元分析结合试验数据，获得随机振动环境下飞行器径向连接螺栓的载荷功率谱密度（PSD）；采用基于弯曲效应的载荷与应力的线性关系，获取螺栓头根部的名义应力功率谱密度；基于Dirlik经验公式，获取应力随机过程的峰值概率密度函数和预期波峰数，联合Miner线性累积损伤模型及经应力集中系数修正的材料S-N曲线，评估径向连接螺栓头根部振动疲劳寿命，获得的结果与试验螺栓头断裂现象符合，并确定螺栓断裂原因为低频共振疲劳。

Analysis of vibration fracture of radial connection bolt of aircraft

The Power Spectrum Density (PSD) of the radial connection bolts of an aircraft in the random vibration environment was obtained combing finite element analysis with test data. The linear relationship between load and stress based on the bending effect was adopted to obtain the nominal stress PSD of root part of radial connection bolt. The peak value probability density and the expected wave crest number in the stress stochastic process were obtained by using Dirlik empirical formula. Based on the Miner fatigue damage theory and the material S-N curve revised by the stress concentration coefficient, the vibration fatigue life of root part of radial connection bolt was estimated. The result was consistent with the countersunk bolt fracture in the random vibration test. It is confirmed that the reason for connection bolt fracture was low frequency resonance fatigue.