基于超椭球模型的飞机液压刹车系统故障树分析

THE FAULT TREE ANALYSIS OF AIRCRAFT HYDRAULIC BRAKE SYSTEM BASED ON HYPER-ELLIPSOIDAL MODEL

采用基于超椭球模型的故障树分析方法来解决飞机液压刹车系统故障树中底事件故障率概率统计信息不充足的问题,并对该系统进行可靠性评估。根据液压刹车系统原理和故障机理建立系统故障树,引入超椭球模型来描述底事件不确定性,推导了系统顶事件失效概率以及各底事件重要度基于双层蒙特卡洛法的仿真流程,并与区间模型下故障树分析进行对比。结果表明:超椭球模型下的故障树分析只需要底事件失效概率取值范围,而不要求精确的概率统计信息,且相对于区间模型,其结果更加精细,更加符合工程实际。同时通过底事件重要性测度分析可以确定关键失效事件,为刹车系统改设计及重点维护提供指导。

In fault tree analysis of aircraft hydraulic brake system,the probability statistical information of failure rate for bottom event is usually not sufficient.To solve this problem,a fault tree analysis method based on hyper-ellipsoidal model was given.Firstly,according to hydraulic brake system principle and the failure mechanism,the system fault tree model was established.Then the hyper-ellipsoidal model was introduced to describe the uncertainty of bottom event.Finally,the simulation process of system top event failure probability as well as the importance of bottom events was deduced based on double Monte Carlo method,and comparison was made with fault tree analysis under interval model.Results show that the fault tree analysis method under hyper-ellipsoidal model just needs the value range of bottom event failure probability,without requiring the detailed probability statistical information of bottom event.Compared with the interval model,the hyper-ellipsoidal model exhibits stronger robustness,and its results meet the engineering practice better.At the same time,the importance measurement analysis of bottom events was conducted to identify key failure events,which provides guidance for the brake system in design and maintenance.