Studies On The Method Of Reliability Growth Test Evaluation For Liquid Rocket Engine

There are some characteristics for reliability growth test evaluation (RGTE) of liquid rocket engine, such as its field test data is small sample, there are multi-kind stresses act on the system during accelerated life test, its life test data belongs to a dynamic parent population. So, it is difficult to obtain a scientific analysis result of the reliability growth test data by classical statistical method. In this paper, based on the Bayes method, the evaluation method for general system's reliability growth test with small sample is studied, and the research result is used in the reliability growth test evaluation of some liquid rocket engine. The contributions of this paper are as follows.To the analysis of accelerated factor, as far as the exponent, weibull, log-normal and normal distribution is concerned, the Bayes analysis models for accelerated factor are built under the condition of const failure mechanism. Based on the analysis of accelerated factor, the prior distribution of mission reliability under the field test environment is carried out. The Bayes accelerated factor analysis model can provide a reasonable solution for such an important problem in1 classical accelerated life test analysis that the field test data is small sample so the analysis for accelerated factor is unreachable or its accuracy is relatively bad.To the establishment of prior distribution in RGTE, considering that reliability growth test data belongs to a dynamic parent population, and based on the stage reliability growth test data, the dynamic modeling methods for prior distribution establishment are studied. In this paper, the prior distribution dynamic modeling methods such as the conversion of stage reliability test information, linear regression analysis modeling method, ML-II method, conversion of similar system's information, the information of replacing component, and the method by using reliability growth model, are studied. By constructing dynamic modeling methods, this paper solves the key problem of prior distribution establishment in RGTE when using Bayes method. And the dynamic modeling method provides a theoretic basis when using Bayes method to evaluate the reliability growth test under the condition that the field test data is small sample and its stage test result belongs to a dynamic parent population.To the fusion of prior information, by using AHP and synthesis factor method that based on experts' opinion, the weight factor calculation methods are respectively presented. According to the theory of empirical Bayes and spline function, the prior information fusion method is proposed. With the prior information fusion method, such a problem in RGTE can be solved that the field test data is small sample, so it is difficult to give the prior distribution weight based onthe consistent test of prior information. Especially, by using the empirical Bayes theory, the prior information fusion method based on spline function can greatly decrease the subjectivity during fusion process.To the analysis of robustness of prior distribution, the hypothesis testing models of prior distribution robustness analysis for binomial, normal, exponent and weibull distribution are established. The establishment of robustness analysis model provides a simple and convenient tool in the rationality verification of prior distribution.To the evaluation of liquid rocket engine reliability growth test, combined with the characteristics of liquid rocket engine system, the Bayes-Binomial model and Bayes-Weibull model are build to analyze the reliability growth test data, and their analysis results are compared with classical methods to illustrate the validity of Bayes method. To the performance reliability evaluation, the Bayes-Normal model is built. The application of RGTE theory can provide an effective tool to evaluate the liquid rocket engine reliability growth test with the characteristics which is described in the first paragraph. On the foundation of above theory for RGTE, the software for liquid rocket engine reliability evaluation is devel...