Estimation method for random sonic fatigue life of thin-walled structure of a combustor liner based on stress probability distribution

摘要

As to the sonic fatigue problem of an aeroengine combustor liner structure under the random acoustic loadings, an effective method for predicting the fatigue life of a structure under random loadings is studied. Firstly, the probability distribution of Von Mises Stress of thin-walled structure under random loadings is studied, analysis suggest that probability density function of Von Mises stress process accord approximately with two-parameter Weibull distribution.The formula for calculating Weibull parameters are given.Based on the Miner linear theory, the method for predicting the random sonic fatigue life based on the stress probability density is developed, and the modal for fatigue life prediction is constructed. As an example, an aero-engine combustor liner structure is considered. The power spectrum density(PSD) of the vibrational stress response is calculated by using the coupled FEM/BEM method, the fatigue life is estimated by using the constructed model. And considering the influence of the wide frequency band, the calculated results are modified. Comparetive analysis show that the estimated results of sonic fatigue of the combustor liner structure by using Weibull distribution of Von Mises stress are more conservative than using Dirlik distribution to some extend. The results show that the methods presented in this paper are practical for the random fatigue life analysis of the aeronautical thin-walled structures.