飞机重心过载谱低载截除水平确定方法研究

A Method for Determining Small Load Cycles Elimination Level of Aircraft G-factor Spectrum

飞机疲劳研究中的过载谱低载截除目前尚局限于经验方法,截除标准以循环幅值标准和循环数量标准两种形式并存,两种标准的截除水平也不统一。为此,根据重复载荷源发生规律和飞参记录特征,提出了过载谱低载截除水平确定的"定界找点"方法,给出两种标准相结合的工程应用方案,对基于经验的传统截除方法进行了理论探索。结合某型直升机的实例说明了该方法的实现过程,在置信度0.95下的最佳截除水平点为129次/飞行小时,对应的循环幅值标准为0.0823 g。

For g-factor spectrum,it is difficult to find a certain criteria for small load cycle elimination,and the work still relies on experience so far.Further more,there are two kinds of eliminating criterion at the same time： amplitude threshold and cycle quantity.By considering repeated loading sources and flight data record characteristics,a new method called ＂Setting Limits and Searching Point＂ is brought forward on the basis of elimination level mathematic model.Such a method was helpful for turning traditional experiential practice to theoretical exploring.A scheme combining both criteria is introduced for engineering application.Finally,an example for a certain helicopter′s g-factor spectrum elimination is presented to demonstrate the engineering process and to prove that the method is feasible.Under the confidence level of 0.95,the best elimination level in cycle quantity is 129 times/fh（flight hour） and the corresponding elimination level in amplitude threshold form is 0.0823 g.