阵风载荷谱的损伤分散性研究

Damage variation of gust load spectra

载荷谱的分散性是影响机群疲劳可靠性寿命的重要因素,阵风载荷是运输类飞机重要的损伤来源。为研究运输类飞机阵风载荷谱的损伤分散性,基于离散阵风模型,对调研得到的多个运输机型号的实测阵风速度超越数数据进行了统计分析;假定指定阵风速度下的超越数服从对数正态分布,建立了阵风速度超越数的分散性模型。采用Monte Carlo方法抽样得到单机阵风速度超越数曲线,得到单机随风载荷过载谱,计算得到单机阵风载荷谱损伤,对机群的阵风载荷谱损伤分散进行了研究,结合3个机型的使用剖面进行了算例分析。结果表明:运输类飞机的阵风载荷谱损伤服从对数正态分布,分散性取值与使用剖面密切相关。

Load spectrum variation matters to fatigue reliability service life of a fleet.For transport aircraft,gust load is one of the critical damage sources.To study the damage variation of gust load spectra,two parts have been investigated.In the first process,gust velocity exceedance measured in service of several transport aircraft are statistically analyzed based on discrete-gust model.It is assumed that incremental exceedance of specific gust velocity follows lognormal distribution,and a model of gust velocity exceedance variation is built.In the second process,the damage variation of gust load spectra is studied.With the help of Monte Carlo simulation,gust velocity exceedance curves of aircraft in a fleet are acquired,after which damage of gust load spectra can be calculated.To examine the validity of the methodology,numerical examples are calculated,in which flight profiles of 3 specific transport aircraft are used.The results show that damage variation of gust load spectra of transport aircraft follows lognormal distribution and the values of scatter factor are relevant to flight profiles.