Reliability modeling of competing failure processes with multi-stage degradation

In this paper, reliability models of competing failure processes for the product subject to degradation and random shocks are established, which are accompanied by degradation path slope change caused by specific shock patterns. The two related failure modes are hard failure arising from different random shocks, and soft failure due to consecutive structure damage or combined with a sudden increment of degradation because of an identical random shock. In sophisticated equipment like aircraft engine systems, the degradation path of performance parameters is characterized by multi-stages when the product is more prone to fatigue or accelerated aging, as a consequence of experienced shocks. This article analyzes five random shock patterns that can change the slope of the degradation path and studies an example to explain the application of proposed reliability models as well as the sensitivity analysis of parameters.