Reliability Analysis And Risk Assessment Method And Application Research Based On Fault Tree

Fault tree analysis is an important method for reliability analysis and risk assessment of the system.It is often used in fault diagnosis and prediction,to find the weak links in the system as well as to guide the maintenance and operation.And now it has been widely used in many fields,such as electronics,aerospace,nuclear power,chemical industry,electric power,machinery and other fields.Aiming at the reliability analysis,we study the basic method and theory of traditional fault tree and dynamic fault tree respectively.To avoid the problems that traditional fault tree analysis method based on the cut set has higher complexity in time and space and is not easy to program.In addition,it will produce "combinatorial explosion" problem obviously during the analysis process.we mainly use the method which based on binary decision diagram to solve the fault tree.The core of the method is to order bottom event.For the traditional fault tree,a new sorting method——the minimum depth of the sub-tree is proposed,which is an effective solution of fault tree.This method mainly based on the ranking results of dynamic construct binary decision diagram,which is based on the relationship between the sub-tree of depth and the number of nodes and node of bottom events static ranking.Finally,according to the structured binary decision diagram,implement the minimum cut set of the fault tree fast,which can achieve the purpose of fast reliability analysis of the system.For dynamic fault tree,this paper further improves the minimum depth of the sub-tree method.using the modular thought,transform the dynamic sub-tree into the corresponding sequence,and then sorted all the nodes and happened sequence and construct sequence binary decision diagram,according to the structured sequence binary decision diagram,implement the minimum cut set or sequence cut set.Finally,a set of automatic analysis software tool——"fault impact analysis and decision support" system is developed by using fault tree technique.This tool can realize the data analysis and processing,as well as the qualitative and quantitative analysis and other functions of fault tree.In reality,the reliability of the systems or equipment is closely related and inseparable with its size of their risk.Researching the risk assessment after the studying on the reliability analysis method in this paper.Aiming at the risk assessment,the basic method and theory of analytic hierarchy process and triangular fuzzy number are studied in this paper.In view of that evaluation of single value may lead to large deviation of the calculated results by using directly of analytic hierarchy process,triangular fuzzy number and fault tree technology are introduced,and an improved analysis method——triangular analytic hierarchy process is proposed.This method can reduce the error between the analytical results and the real values to the maximum extent.And also directly structure the hierarchical structure model through the fault tree model,we can be able to save time and effort at a certain extent.In the end,as a case study,the reliability analysis and risk assessment for satellite reaction wheel are carried out by using the proposed fault tree analysis method and the triangular analytic hierarchy process,and the correctness of the analysis method is verified each other by the analyzed results.The results show that the reliability analysis and risk assessment methods which we proposed in the text have certain feasibility and practicability.