Reliability assessment for bolt joint system with multiple dependent competing failure processes

In this paper, a novel reliability model for bolt joint systems is proposed, which incorporates multiple dependent competing failure processes (DCFP). The multiple DCFP model is constructed by the DCFP of individual bolts and the bolt joint system. The DCFP model of a component is developed by hard failure due to fatal shocks and soft failure resulting from degradation. The component failure process is stochastic dependent, as the stochastic shock process affects both the hard and the soft failure processes. Additionally, a system failure model is established by arranging N components in a circle, which is location-dependent. The failed components lead to either a K/N failure model or a k/r/N failure model for the bolt joint system. In the K/N (F) system model, failure occurs when the number of failed components (NOFC) reaches K . For the k/r/N system model, failure occurs when the NOFC reaches k within any consecutive r set out of N . A closed-form formula is derived from the system reliability model, which is applicable when there are fewer than two separate k/r/N patterns. The practicality of the proposed model is demonstrated through a case study involving a bolt joint system.