Research on Common Mode Analysis Method in System Safety Analysis

Abstract

In system safety analysis, the existence of Common Mode Failure (CMF) greatly undermines the independence of components and poses great threat to safety of the system. In Common Mode Analysis (CMA), whether CMF needs to be considered for basic events under different types of logic gates in Fault Tree, it lacks strict reasoning and comprehensive consideration. This paper takes CMF of the same and different levels under "AND gate" and "OR gate" in fault tree as an example, and uses reasoning analysis and mathematical calculation methods to compare the influence of the existence of CMF on failure rate of the system. The results show that whether CMF need to be considered for the component depends on the type of logic gate correspond to the higher-level component. The research results have certain reference value for the analysis of CMF in CMA.