Combined Model Of Phased-mission System Under The Condition Of Common-cause Failures

Many high security systems in the field of aerospace, nuclear power industry, communication network, machinery and electronic actually are Phased-mission Systems. High reliable components and redundancy technology are used in the these systems.The effect of the failure of a single component on the system is getting smaller and smaller, but the proportion of system failure caused by the dependent failure of components is increasing. Common-cause failures is an important cause of dependent failure. Therefore, it is necessary to consider the influence of common cause failure as accurately evaluating the reliability of complex systems. However, the existing methods for reliability analysis for the common failures have encountered severe difficulties in model scale and computational complexity.In this paper, we mainly study the simple methods of multi stage systems with common cause failure. Two simple solution for the failure of two cases of common failure is proposed. The study include two parts:A simple method for reliability analysis of PMS in the case of internal CCF is proposed. PMS with the single point failure suffering the propagated failures is considered. A single point failure and propagated failures model(SFPFM) that divides PF into two types is established. Base on the SFPFM, At first, the IPC and the combination model are separated by the SEA algorithm and then the propagated failure is classified into group. When system meets certain conditions, a numerical example shows that the method is more advantageous than the existing analytical method.A simple method for PMS reliability analysis is proposed for the case of external CCF. By analyzing the failure behavior of components, the relationship diagram of the common cause failure and component is established. Based on the graph, the decomposition method of the external common cause failure is optimized to reduce the number of the sub models. For the PF in the sub models, the complete group separation method(I-GSEA) for simplifying the model scale is used to simplify the computation. Finally, the effect of common cause failure on system reliability is verified through case analysis, and the validity and accuracy of the synthesis method are explained.