Reliability evaluation of DCFP in k/n system considering shock threshold descending

In the industrial design process, redundant methods are often used to improve the reliability of the system, for example the k-out-of-n system. Also, degradation and overstress failure exist in the many systems where operation load and environmental conditions are complex. They can cause DCFP (Dependent Competing Failure Process). However, the components in k-out-of-n system often have load-sharing effects, and the failure correlation caused by them may increase the joint failure probability of the system and reduce the reliability of the system. Moreover, systems may experience the mutual effect of the degradation and catastrophic failure caused by shock because of DCFP. After considering the load sharing effect and DCFP in k-out-of-n system, system reliability evaluation becomes more difficult. This paper analyses the relationship about descending of threshold between the interaction of shock process and degradation process from failure behaviour rules. System modelling method and failure probability evaluation are based on considering the impact of load-sharing effects and DCFP in k-out-of-n system. The study considers three mechanisms of descending load threshold: 1) degradation failure threshold descending caused by random shock process; 2) shock failure threshold descending caused by random shock process; 3) shock failure threshold descending caused by degradation process. Finally, this paper studies the reliability of the system by simulating the case of a voltage regulator system by considering load-sharing effects and DCFP to evaluate the influence of threshold decrease on k-out-of-n system.