Research On Aero-engine Reliability Modeling And Evaluation Method Based On Stochastic Process

As the core power source of the aircraft,the reliability of aero engines is directly related to the performance and operational safety of the aircraft,and is also the basis for making maintenance decisions.Aero-engines have the characteristics of high reliability and long life.In the case of less failure data,the airway system performance monitoring data can be used to evaluate the reliability of aero-engines.Stochastic processes have been widely used in degradation modeling in recent years because they can well express the disorderly changes of products over time.Therefore,this paper starts from the perspective of performance degradation,and conducts reliability modeling and evaluation of aero-engines based on the degradation modeling method of stochastic process.The main research contents are as follows:(1)Reliability analysis of aero-engine under multivariate degradation based on stochastic process.Through the analysis of the working principle and failure mode of aero-engines,the exhaust temperature margin and fuel consumption deviation are selected as performance degradation monitoring indicators,and the Wiener process and Gamma process are used to establish a single performance degradation model.Then consider the reliability modeling research of multiple performance indicators,establish a multiple degradation model based on the Copula function,and select the optimal Copula function through the model comparison criteria;finally,compare and analyze the situation where a single degradation index and two independent degradation indexes are used.Complete the reliability assessment of the aero engine.(2)Reliability analysis of aero-engine based on multivariate degradation modeling under competitive failure.First,considering the nonlinearity and individual differences in the degradation process of aero-engine systems,the nonlinear Wiener process and Gamma process with random effects are used to describe the system degradation failure process;secondly,the appropriate Copula function is selected to analyze the failure correlation of the multivariate degeneration system.Modeling,considering that there are many unknown parameters of the model,the Markov chain Monte Carlo method is used to estimate the parameters of the multivariate degradation-related failure model;at the same time,considering that the degradation failure is accompanied by the sudden failure,the Weibull distribution is introduced to describe the sudden failure time,and the proportional hazard is used The model constructs a sudden failure rate function on the amount of performance degradation,and uses a two-step maximum likelihood estimation method to identify model parameters.Finally,use the built model to evaluate the reliability of the aero-engine.(3)Reliability analysis of the relevant competitive failure process considering external shocks.Aiming at the competitive failure system that undergoes both the performance degradation process and the external impact process in engineering practice,assuming that the internal degradation of the system is a general degradation process and the external impact is an extreme impact process,analyze the degradation amount,degradation rate and The changing law of the failure threshold.A reliability model of competitive failure system based on multistage variable degradation rate and failure threshold is established.The Monte Carlo simulation method is used to solve the reliability,and the sensitivity analysis of different system parameters in the reliability model shows that each parameter has different degrees of influence on the reliability of the system.