The Study On Reliability Growth Management For Liquid Rocket Engine

Taking as the background of some liquid rocket engine, the thesis studies completely and systematically the theory and method of reliability growth management for liquid rocket engine. The thesis is partial fruit of the task "Liquid rocket engine reliability growth analysis and evaluation". Liquid rocket engine is key power equipment for carrier rocket engine, to meet the demand of higher performance; its structure is more complex. The reliability of liquid rocket engine is an important technology index. According to statistics of American carrier rocket that have been published, over sixty percentage of failure cause is power equipment. So, high working condition and long test time is need to reliability growth. But in China, liquid rocket engine has small test sample and little test time because of the restriction of development expenditure and period. It is necessary to use reliability growth management, put test, analysis and correction into a scientific management framework controlling reliability growth and utilize limited resource reasonably to reach the demand for reliability. There are still many problems using current reliability management method for liquid rocket engine. As to the charactersis of liquid rocket engine test, the reliability growth management theory and engineering application for liquid rocket engine have been studied. The primary work of the thesis includes:(1) Reliability information is the base for reliability growth; accuracy and amount determine the validity of reliability growth analysis, plan and decision. For the small sample of system test, fly data and ground test data are expanded to fly data, ground test data, similar product test data, component data, expert information and simulation test data. Expanding information is separate, stochastic and temporal. Information management method and process for liquid rocket engine have been studied. And parallel management and integrated management are used to liquid rocket engine reliability growth management. (2) The method of expanding information has added the information at same as bringing the difficulty of information utilization. Furthermore, sample is dynamic during reliability growth, which added the difficulty of information utilization. Information fusion method has been brought forward to utilize multi-source reliability growth information. Information fusion models of same source and phase, multi-source and reliability growth are built. Through the above three models, we can get comprehensive and exact information for liquid rocket engine.(3) As to reliability growth management being an uncertain decision based on imperfect information, FMEA and fault diagnosis model have been built for liquid rocket engine. FMEA is an important tool for reliability growth and a qualitative method. Usingqualitative and quantitative method, whole complex system FMEA model based on Bayesian networks has been built, which unify severity and failure probability into one framework. The accuracy of fault diagnosis determines the actual reliability growth. The fault diagnosis model based on Bayesian networks can solve uncertain decision and competitive risk problem. Test indicates that the rate and veracity of BN fault diagnosis model is better than other fault diagnosis models. Furthermore, the BN fault diagnosis model can finish the diagnosis task when the available numerical probabilistic information is incomplete or partially correct. Leaky Noisy-or model and sensitivity analysis also been used in Bayesian networks model to reduce the data demand and increase the concluding efficiency.(4) The grading reliability growth plan model has been built. The model based on the result of reliability growth information fusion, use MTGP model to tracking reliability growth. The model can predict and decide to overcome the shortcomings of Bayesian reliability growth models. The model has the advantages over other models, such as according with project practice and high maneuverability.(5) Risk decision method of liquid rocket engine based on uncertain and i...