Study On The Automatic Construction And Analysis Method Of Multi-state Fault Tree For Complex Systems

With the development of science and technology,more and more large and complex systems are needed,and system reliability design is especially important in this field.Fault Tree Analysis(FTA)is a method used to analyze and evaluate the safety and reliability of large and complex systems.It is also one of the globally recognized methods for assessing system reliability and safety.The basis of the FTA is the Fault Tree.When constructing fault trees of large and complex systems,artificial fault tree construction takes time and human resources,is inefficient,and has been gradually eliminated.Computers have the advantages of large amounts of stored information and convenient operation.Computeraided fault tree construction has become mainstream.This thesis improves the automatic fault tree construction method of negative feedback system,and also proposes the automatic fault tree construction methods of feedforward,nested and header structures.The idea is described as follow: At first,we need describe the system components and system structure models in a standardized method.User only need to build a system components' library,draw a structural model diagram of the system,and use drag and drop to build the system structure with the components' library and the identification library.The identifiers in the system mark the feedback,feedforward,redundancy,nesting and other structures in the system.Secondly,when we specify the top event of the given system,the computer can identify and process the complex structure in the system according to the algorithm,and automatically generate the final standardized fault tree.In this paper,the feed-forward,feedback and nested system structures are used as examples to automatically generate fault trees,and the qualitative and quantitative analysis are also performed on the fault tree that consists of a feedback structure.Based on the results of these two analyses,the weak points of the system can be found and system's reliability can be improved.These methods have practical significance for tracing the bottom faults,and they are convenient for further analysis of system reliability.These method can also be used in other control systems.