A novel reliability model for multi-component systems subject to multiple dependent competing risks with degradation rate acceleration

The failure of a system is usually caused by internal degradation or external random shocks. The failure caused by internal degradation is called soft failure, such as erosion, fatigue, wear, etc. And the hard failure is caused by external random shocks, such as device breakdown, short circuit, etc. The degradation processes for components in a system and a shock process arriving at the system compete with each other. The occurrence of any failure mode may lead to the failure of systems. A system deteriorates with its use and age, which is a continuous accumulation of degradation. However, the hard failure may or may not happen in its life cycle. In many studies [10, 14, 28, 32], the competing risks were treated as independent. However, the natural degradation processes of a system are usually affected by the shock loads. That is, the same shock arriving at a system will influence the degradation process of each component. Hence, the assumption of independence between competing risks is not reasonable, and it may cause underestimation or overestimation of the system reliability. It is very necessary to consider the dependence relationship between multiple degradation processes and a shock process when establishing the reliability model for a system. Recently, some researchers [5, 15] have taken the dependence relationship into account to develop the reliability model of a system. Peng and Feng [20] built a reliability model for the system subject to multiple dependent competing risks, where dependent competing risks referred to soft failure and hard failure. Soft failure was caused by continuous natural degradation and additional SDI due to random shocks. Hard failure was induced by fatal shock loads from the shock process. Jiang and Feng [11] proposed a reliability model for a sysYanjing ZhAng Yizhong MA Linhan OuYAng Lijun Liu