Modeling ageing effects in the context of continuous degradation and random shock

Abstract This paper explores how the product’s intrinsic capacity to resist the exposed failure processes ages with operation. Ageing effects on continuous degradation and random shock are specified respectively. The degradation process is modeled by a Gamma process with a monotonically increasing shape function of which increase rate is determined by the ageing intensity. Ageing impact on the hard failure is also considered by assuming that the critical threshold decreases with operation and the decrease rate is the function of ageing intensity function. The dependence strength between the degradation process and the ransom shock is developed based on the shock magnitude and the cumulative ageing probability. Reliability functions for soft, hard and competing failure processes are computed respectively with the consideration of ageing effects. An engineering example with regard to cylinder in the engine system is studied to demonstrate how the proposed method can be applied to the engineering practice.