Study On Momentum Wheel Reliability Modeling Considering Performance Degradation

The momentum wheel(MW)is a typical electromechanical coupling product with small sample,high reliability and long life.It is widely used in satellite attitude control systems.It is difficult to evaluate the reliability through a large amount of failure data because of the complex failure mechanism,the poor working environment,and the variable working stress.However,we can obtain the degradation data of the product,which contains rich product reliability information,by measuring the change of a certain performance index of a product over time.Therefore,it is favored by many scholars and is one of the effective means to study the reliability of high reliability and long life products.Therefore,this paper intends to use the reliability modeling method based on degradation data to carry out reliability related research on the momentum wheel.The main research contents are as follows:(1)Consider the reliability modeling of multivariate correlated degradation process.Firstly,use Wiener stochastic process modeling the reliability of individual product degradation indicators.Then,considering the situation that existing multiple degradation index during the service of the momentum wheel,the Copula function is introduced to characterize the correlation between degradation index.Then,establish the multivariate correlated degradation model of the product,and study the applicability of the Copula function through the model comparison criterion.Finally,evaluate the reliability of the momentum wheel,and compared the multivariate correlation model with the independent model.(2)Reliability modeling research considering individual differences.Aiming at the individual difference between different products,a certain parameter in the stochastic process model is assumed to obey a random distribution,so as to establish a Wiener process model and a Gamma process model considering individual differences.Then,use the EM algorithm and the Bayes theory estimated the parameters,respectively.Finally,evaluate the reliability of the momentum wheel using the model.(3)Reliability modeling research considering external impact and internal degradation.Considering the engineering practice of abrupt failure and degradation failure,the momentum wheel reliability modeling method with external impact and internal degradation is studied.Then,introduce the concept of effective impact threshold,and assume that the external impact obeys the Poisson distribution.Different shock models are used to establish the relevant competitive failure model between the degraded failure and the abrupt failure.Finally,the model is verified by a case study.