基于改进DEMATEL-ISM模型的机轮刹车系统风险因素分析

Risk factors analysis of the wheel brake system based on the improved DEMATEL-ISM

针对机轮刹车系统在飞机着陆阶段复杂的安全性问题,应用系统理论过程分析法(STPA)识别潜在风险因素,采用风险熵改进决策实验室分析法(DEMATEL)计算风险因素中心度和原因度,确定因素重要性和属性,并集成解释结构模型法(ISM)建立风险因素递阶层次结构。结果表明:在因素辨识方面,STPA与传统FTA方法相比,可识别出更多的风险因素,如组件交互、设计缺陷等因素;通过改进DEMATELISM可体现系统因素客观联系,并确定AACU为系统关键部件,且风险因素可分为3个层次,在层次内与层次间均存在因素关联,从递阶层次结构分析得出可采取断链措施和提高部件可靠性来保障系统安全。

Aiming at the complex and complicated safety problems of the wheel brake system( WBS) during the landing stage,we have done an analysis on the safety of the operational stage to identify the risk factors and determine their relations. To achieve the purpose,first of all,we have adopted the system theory process analysis( STPA) to identify the safeless or reckless control activities concerning the risk factors by building up a controlfeedback structure model under the control relations and the operational principles. And,then,we have managed to change the risk entropy to characterize the uncertainty with the probability of the event occurrence of the direct influential matrix in the decision making trial and the evaluation laboratory( DEMATEL).According to the improved DEMATEL-ISM,the centrality degree,cause degree and the order of the centrality degree can be obtained to confirm the causal relevance and the key indexes.And,finally,on the above series of analyses,it would be necessary to integrate the interpretive structural model( ISM) to gain the reachable set and the forward set under the given threshold,as well as to gain their intersection set. As to the intersection set,the reachable matrix can also be set up to build up a system hierarchical structure to reflect the intrinsic and hierarchical relation of the factors concerned graphically. The results of the above study can indicate that,as compared with the FTA,the STPA can help to identify and determine more risk-leading factors besides the component failure,such as the interactive factors and the designing defects. Through the above said improved DEMATEL with ISM,the objective relation of the system factors can be effectively reflected and clarified. At the same time,the AACU can be confirmed as the key component,which should have the greatest impact on the system safety. In the mean time,the risk factors can be divided into 3 levels to reflect the relation in and out of the hierarchical system. From the hierarchical structure above mentioned,it can be seen that the system safety can be guaranteed and ensured by taking measures to break the chain and heighten the component reliability.