针对飞机液压管路连接件疲劳断裂问题,基于随机振动理论对带有轴向装配偏差的液压导管进行疲劳寿命预估.从建立真实飞机液压系统管路连接件有限元模型入手,分析轴向装配偏差产生的装配应力对结构的影响规律,通过试验获取不同轴向偏差下的管路连接件的阻尼比.利用有限元分析软件进行随机振动分析,获取危险部位的应力响应功率谱密度函数,结合Miner线性损伤理论,对含有装配应力的管路连接件进行了随机振动疲劳寿命预估.设计并进行了管路共振疲劳试验,发现管道裂纹萌生位置及疲劳寿命下降趋势与仿真结果契合,仿真及试验结果表明当轴向偏差达到 0.8 mm时,严重影响到了飞行安全.研究成果为航空液压管路的设计及装配理论研究提供理论参考和技术支撑.
Aiming at the fatigue fracture problem of aircraft hydraulic pipeline connector,the fatigue life of hydraulic conduit with axial assembly deviation was predicted based on random vibration theory.Starting with the establishment of the finite element model of the pipeline connector of the real aircraft hydraulic system,the influence law of the assembly stress caused by the axial assembly deviation on the structure was analyzed,and the damping ratio of the pipeline connector under different axial deviation is obtained through the test.The random vibration analysis was carried out by using the finite element analysis software,and the stress response power spectral density function of the dangerous part was obtained.Combined with Miner linear damage theory,the random vibration fatigue life of the pipeline connector with assembly stress was predicted.The resonance fatigue test of pipeline was designed and carried out.It is found that the crack initiation position and the decreasing trend of fatigue life of pipeline are consistent with the simulation results.The simulation and test results show that when the axial deviation reaches 0.8 mm,it seriously affects the flight safety.The research results provide theoretical reference and technical support for the design and assembly theory of aviation hydraulic pipeline.