A Multi-Degradation Model Subject to Dependent Competing Failure Processes

Considering the zoned shock effeteness, a multi-degradation system model subject to dependent competing failure processes is developed in this paper. The multi-degradation is constructed by the degradations in both a soft failure model and a hard failure model. Reliability assessment of the soft failure model has been widely studied, but degradation in a hard failure process with an extreme shock model has been rarely studied. The existing methods adopted approximate approaches to evaluate extreme shock model reliability with threshold degradation, which could not satisfy the accuracy requirement of system reliability calculation. To improve the calculation accuracy, a multi-degradation model subject to stochastic-dependent competing failure processes is investigated in this paper. A distribution-based algorithm is developed to calculate the extreme shock model reliability with threshold degradation. Furthermore, according to the effect of the shock process in the hard failure process, threshold degradation can be divided into degradation caused by both the zoned shock process and general degradation. Consequently, the closed-form formulas for system reliability with the multi-degradation model are derived. A case study is employed to illustrate the developed model, and the effectiveness of the algorithm is validated through Monte Carlo simulations.