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Research On Reliability Modeling And Analysis Methods Based On The Performance Degradation

Posted on:2016-10-20Degree:DoctorType:Dissertation
Country:ChinaCandidate:R YuanFull Text:PDF
GTID:1222330473956128Subject:Mechanical and electrical engineering
Abstract/Summary:PDF Full Text Request
Reliability is a main powerful tool to improve the safety of products, which relates to the personal safety and the socioeconomic benefits. Therefore, more and more researchers have paid intensive attentions to the reliability research from both the academia and industry since 1950 s, when reliability was born. Through the development of more than half a century, reliability theory and method has been increasingly applied to a variety of important fields, such as nuclear power, transportation, machinery, electronic, aerospace, etc. However, the traditional reliability is mainly based on the Probability theory which often utilizes lots of failure data to calculate and evaluate the reliability. With the rapid development of technology, the major equipment also leads to high precision, complex and multi-functional. In addition, with the application of new materials, new process and new technology, the requirement on reliability of the equipemt has become more and more stronger. In such cases, it is difficult to obtain enough failure data in a relatively short period. Therefore, few or no failure data is one of the main reason to constrain the development of reliability.In fact, during the whole life cycle of products, beside the failure data which are collected from the experiments, there are some other data and/or information(such as the performance degradation data) could be available, which also reflect the reliability characteristics to some extent. How to make comprehensive utilization of these data and information has become one of the main methods to resolve the above mentioned reliability problems. If we can make good use of these data and information, many reliability problems will be resolved under the situation with few or no failure data. Thus, in this dissertation, several relevant work has been done on the problem of researching on the reliability modeling and analysis methods based on the performance degradation, and the main contents and achievements of this dissertation are summarized as follows:(1) Reliability analysis considering the performance degradation using the nonlinear fatigue damage accumulation model. In order to improve the accuracy of fatigue damage accumulation, and expand its application range, it is necessary to modify the traditional fatigue damage accumulation model. Based on the Manson-Halford’s damage curve approach, a modified damage curve approach is proposed by introducing a concept of load amplitude ratio. This model considers not only the load sequence effects, but also the effects of load interaction, thus it has a wider applicability. In addition, a modified nonlinear fatigue damage accumulation based on continuum damage mechanics theory is developed, which can reflect the essence of fatigue damage accumulation. Moreover, it considers the effects of many factors to the continuum damage, such as the macroscopic characteristics of energy dissipation, average stress, maximum stress, cyclic hardening and cyclic softening and so on. Then taking the relationship between the fatigue damage accumulation and the performance degradation into account, a performance degradation analysis method is proposed, which is based on the modified damage curve approach by introducing a degradation coefficient into the damage accumulation model. The example analysis results show that the proposed method is accurate and reasonable.(2) Reliability analysis of the performance degradation using saddlepoint approximation method. For the problems of few or no failure data to the traditional reliability analysis, the saddlepoint approximation method is proposed for reliability analysis of the performance degradation. In addition, combining the characteristics of performance degradation data, the reliability analysis method of degradation path model and stochastic process model are used to validate the proposed method. Finally, based on the degradation data of GaAS laser, the reliability evaluation is conducted through the above mentioned models and methods.(3) Reliability analysis method considering the external shocks and the performance degradation. First, for the catastrophic failure, the Poisson process is used to describe the external shocks, and according to the Stress Strength Interference(SSI) theory, the catastrophic failure analysis which is caused by the external shocks is constructed by the extreme shock model. Second, for the degradation failure, the effect coefficient of external shocks is introduced to calculate the damage accumulative effect of external shocks to the internal degradation, and based on the additive model, the performance degradation analysis mothod considering the effects of external shocks is proposed, which can effectively consider the interaction of the external shocks and the internal degradation. Third, sensitivity analysis is discussed to illustrate the effect of failure threshold to the reliability and failure rate. Results show that the proposed method can effectively calculate the system’s reliability under the catastrophic failure and the degradation failure.(4) Reliability analysis method under the accelerated degradation test. The models of the step stress accelerated degradation test of the Wiener process and the Gamma process are constructed, which are combining the classical accelerated performance degradation equation with the performance degradation analysis of the Wiener process and Gamma process. In this model, Bayesian theory is used to fusion the expert experience information and the previous performance degradation data with the accelerated degradation test data. Moreover, in order to resolve the problem of no direct analytical solution in this framework, Markov Chain Monte Carlo(MCMC) simulation is used, which can effectively expand the application of this framework. Using this framework, the issues on the determination of accelerated factors, the increasing of model parameters, the reducing of sample size and the analyzing of confidence degree are effectively solved.
Keywords/Search Tags:fatigue damage accumulation, saddlepoint approximation, catastrophic failure, degradation failure, accelerated performance degradation, Bayesian theory
PDF Full Text Request
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