Abstract
This paper considers competing failure propagation and isolation effects in the reliability analysis of systems with functional dependence, where the failure of some trigger component causes other components (referred to as dependent components) to become inaccessible or isolated from the system. A propagated failure originating from a dependent component could affect other parts of the system and thus cause the entire system to fail. However, if the trigger component fails first, the propagation of the dependent component failure can be prevented and thus it cannot affect the function of the rest of the system. In other words, propagated failures originating from dependent components in systems with functional dependence can have different consequences due to their competition with the failure of the trigger component in the time domain. This paper suggests a combinatorial method to address such competing failure behavior in the reliability analysis of non-repairable binary-state systems. Different from the work reported in the literature that assumes local and propagated failures of a component being mutually exclusive, the proposed method is applicable to independent and dependent local and propagated component failures. The system reliability analysis results for all the three cases (mutually exclusive, independent and dependent) are compared through a case study. The proposed method is verified through comparison with Markov-based methods.