基于频域分析的机载液压驱动装置疲劳寿命预测方法研究

Fatigue Life Prediction Method of Airborne Hydraulic Drive Based on Frequency Domain Analysis

目的 采用时域雨流法和4种频域振动疲劳分析方法对机载液压驱动装置的危险部位进行寿命预测及频域方法适用性研究。方法 首先通过有限元随机振动分析得到该结构耳片危险区域的应力PSD,计算的谱宽系数都集中在0.3~0.35,是窄带和宽带分界区域。然后运用4种典型的载荷谱估计模型,即三区间法、基于Dirlik雨流幅值经验模型、用于窄带过程的Rayleigh分布模型、Weibull分布模型,得到危险位置的疲劳寿命安全系数。接着将应力PSD映射为应力-时间序列,并基于雨流计数法得到疲劳寿命安全系数。最后以时域疲劳预测结果基准,对4种频域方法的适用性进行讨论。结果 预测结果显示,Dirlik方法预测的9个安全系数最为可靠,Rayleigh法结果一般,三区间法和Weibull法最差。结论 在窄带和宽带分界区域的谱宽系数,建议采用Dirlik方法,不建议采用三区间法和Weibull法。

The work aims to employ the timedomain rainflow method along with four frequencydomain vibration fatigue analysis techniques to forecast the lifespan of critical locations in an onboard hydraulic drive and study the suitability of fre-quency domain method.Initially,the finite element random vibration analysis was carried out to obtain the stress PSDs in the critical areas of tabs of the structure.The calculated spectral width coefficients were uniformly clustered within 0.3 to 0.35,marking the transition zone between narrowband and broadband.Subsequently,four representative load spectrum estimation models,namely the three-interval method,the Dirlik rainflow amplitude empirical model,the Rayleigh distribution model and the Weibull distribution model for narrowband processes,were utilized to determine the fatigue life safety factors at the critical locations.The stress PSDs were then transformed into stress-time series,and the fatigue life safety factors were calculated by the rainflow counting method.Lastly,the suitability of the four frequencydomain methods was deliberated against the benchmark of the timedomain fatigue prediction outcomes.The findings indicated that the nine safety factors derived from Dirlik's method were the most trustworthy,with generally reliable results from Rayleigh's method and notably inferior outcomes from the three-interval and Weibull methods.In the transition zone between narrowband and broadband,the Dirlik method is recom-mended over the three-interval and Weibull methods.