Reliability Research Based On Dynamic Fault Tree

With a clear sense of graphical symbols,Dynamic Fault Tree method can directly show the operation mechanism and failure process of the system by converting the structural modeling system to Graphical analysis and research model, and It has a better modeling and analysis capabilities for the dynamic system with combining the merit of Markov model. DFT does not have the ability of analysis,so it must combine with other analytical methods. A complex DFT model is usually dealt by the modular approach,through which the model is divided into several small models, which can effectively improve the efficiency of the analysis model. Therefore, the reliability analysis methods based on DFT model are widely used in many fields.Reliability Distribution and reliability analysis are two important contents in Reliability Engineering, which are importantance of the system evaluation and design. Following research does for the deficiencies of the prior analysis methods.The existed reliability analysis methods based on DFT can only solve the steady-state reliability of the system and not the instantaneous probability,which is the the best system reliability metrics. For the above, through the combination of DFT advantages and statistical correspondence in Hidden Markov Random Process,a DFT reliability analysis method based on Hidden Markov Model is given. And it is applied to the Avionics Full Duplex Switched Ethernet to calculate the instantaneous reliability according to a given sequence of observations.A reasonable allocation model has an important guiding significance for high reliability system. Reliability distribution methods existed can only deal with system with static characteristics, and unable with complicated structure or dynamic characteristics. Due to corresponding to expected allocation principles, the AGREE allocation method becomes one of the widely used reliability allocation method. Combining the advantages of DFT modeling and the allocation principles of AGREE method, a reliability allocation method based on DFT moduler and improved AGREE is given. Appling it to static and dynamic fault tree, it is proved to be a good solution for any structural system reliability.Dynamic Fault Tree analysis based on Multi-valued Decision Diagrams can effectively alleviate the state-explosion problems in Markov chain analysis. However, constructing the corresponding MDD needs a known variable sequence of events. The variable sequence directly affects the size of MDD which come to power level in the worst case, By analyzing the characteristics of using MDD to solve dynamic fault tree and the factors of influencing Binary Decision Diagram variable sequence, a dynamic sequence of events of MDD approach is designed. And it is applied to two simple examples of dynamic fault tree, which proved the correctness and effectiveness of the method by the experiment result.