基于应力概率密度和功率谱密度法的随机声疲劳寿命预估方法研究

针对航空发动机燃烧室火焰筒结构的声疲劳问题,研究了一种用于随机载荷下结构疲劳寿命预估的有效方法。首先,对薄壁结构在随机载荷作用下的Von Mises应力过程的概率分布作了研究,给出了应力峰值概率密度函数的表达式。基于Miner线性理论,提出了基于应力概率密度和功率谱密度法的随机声疲劳寿命预估方法,并建立了疲劳寿命预估模型。以某型航空发动机燃烧室火焰筒结构为例,在采用耦合的有限元和边界元方法计算出随机声疲劳应力基础上,应用所建立的模型进行了疲劳寿命估算,并对计算结果进行了宽带修正。结果表明,该方法对航空薄壁结构随机疲劳寿命分析具有实用性。

Random sonic fatigue life prediction based on stress probability density and power spectral density method

Aiming at the sonic fatigue problem of an aero-engine combustor liner structure, an effective method for predicting the fatigue life of a structure under random loadings was studied.Firstly, the probability distribution of Von Mises stress of a thin-walled structure under random loadings was studied.As a result, the representation of the peak stress probability density was given here.Based on the Miner linear theory, the method for predicting the random sonic fatigue life based on stress probability density and power spectral density was proposed, and the model for fatigue life prediction was constructed.As an example, an aero-engine combustor liner structure was considered.The random sonic fatigue stress was calculated using the coupled FEM and BEM method, then the fatigue life was estimated by using the constructed model.And considering the influence of a wide frequency band, the calculated results were modified.The results showed that the proposed methods are practical for the random fatigue life analysis of aeronautical thin-walled structures.