Reliability Analysis And Maintenance Strategy Optimization For Symmetrical Composite Systems

Symmetrical composite systems are common in mechanical systems,so it is of common significance and engineering value to study symmetrical composite systems.The thesis focuses on failure interaction and the study of reliability analysis and maintenance strategy optimization are carried out.(1)The reliability analysis and modeling of two kinds of symmetrical composite systems with failure interaction have been studied.On one hand,the failure laws of two components in symmetrical composite systems are analyzed quantitatively by the theory of failure rate interaction considering the censored lifetime data.Then the reliability functions of components under different maintenance strategies are derived,and the maximum likelihood model under failure rate interaction is constructed.On the other hand,the failure probabilities of two components in symmetrical composite systems are analyzed using Markov chain method,so as to split the failure data from preventive maintenance to obtain the lifetime data without and with internal impact,and then the maximum likelihood models of independent reliability parameters and internal impact interaction coefficient are constructed.(2)The reliability parameter estimation algorithms under two kinds of failure interaction have been studied.On one hand,the objective functions of independent reliability parameters and failure rate interaction coefficient are constructed by parameter estimation and frequency statistics methods,so as to modify the parameter values of maximum likelihood estimation,and then a reliability parameter estimation algorithm under failure rate interaction is designed.On the other hand,split failure data from preventive maintenance by unequal probability sampling technique and optimization method,and then a reliability parameter estimation algorithm under internal impact interaction is designed.Finally,based on the failure mechanism of symmetrical composite systems with failure rate interaction and internal impact interaction,a lifetime data simulation process under preventive maintenance system is designed.The verification results show that the error between the estimated parameters based on the proposed algorithm and the true values are small.(3)The maintenance strategy optimization of symmetrical composite system with failure interaction has been studied.The mathematical models of three preventive maintenance strategies are constructed respectively.Compared with the results from the maintenance strategy model without considering failure interaction,the results considering failure interaction are more accurate.Influence of different reliability parameters on the results of maintenance strategy optimization are compared,and the results show that with the increase of failure interaction coefficient,the optimal unit time cost increases,and the optimal maintenance interval period shortened.Meanwhile,the shape parameter of reliability function has a significant impact on the maintenance optimization results.(4)Reliability analysis and maintenance strategy optimization for railway wagon bearing systems has been studied.Considering the two kinds of failure interaction at the same time,the reliability model and maintenance strategy optimization model of railway wagon bearing systems are constructed.The differences between estimated bearing reliability functions with and without failure interaction are significant,and the replacement cost minor repair cost have significant impact on the maintenance strategy optimization results.Under the actual maintenance opportunity and cost,the maintenance strategy optimization model of bearing system is built online,the best maintenance strategy is selected,and the best maintenance suggestions are given.