| With the rapid development of civil aircraft in china,security requirements are getting higher and higher,and civil aircraft airworthiness verification and validation technology is also facing challenges.System safety assessment of civil aircraft,as one of the methods of airworthiness verification,is especially important for project development and airworthiness certification.However,the traditional static system safety analysis method usually cannot capture the dynamic behavior of a system such as the sequence of events in time dependence,the replacement of spare parts and priorities of failure events,which is not entirely reasonable for the system.Therefore,dynamic logic gates are introduced in this paper on the basis of static fault tree.Also a dynamic fault tree analysis method for airworthiness is proposed to make up the shortcomings of traditional analysis methods and to enhance the accuracy and applicability of safety assessment methods.First this paper analyzes airworthiness requirements of civil aircraft systems and the relevant industrial standards of system security.And then the process and methods of safety assessment,the analysis work in each aircraft design stage,as well as the application time of FT is expounded in detail.Moreover,dynamic logic gates are introduced to establish the dynamic fault tree with the study of a common analysys method.This method includes modular method for the dynamic fault tree,binary decision diagram method for static subtrees and Markov state transfer chain method.To some extent,this method solves the problem of state explosion by using Markov state transfer chain method separately and reduces the difficulty of calculation.Finally,the method is applied to aircraft wheel brake system to verify its safety requirements.With comparison of analysis results of dynamic fault tree and traditional static fault tree,the feasibility of applying dynamic fault tree to airworthiness safety verification can be shown. |
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