Reliability assessment and lifetime prediction of degradation processes considering recoverable shock damages

Many products degrade over time and their degradation processes could be affected by instantaneous shocks during field usage. Instantaneous shocks can cause incremental increases to the degradation signals through shock damages, and can also increase the degradation rates of products. In practice, some kinds of products can recover fully or partially from shock damages in a certain period of time. In this article, a degradation model for soft failure is proposed considering continuous degradation processes with recoverable shock damages for reliability assessment and lifetime prediction of products. The random component of the degradation processes is characterized by a Wiener process and the effect of instantaneous shocks on the degradation process is expressed by an exponential function with a residual effect for either partial or full recovery. The impact of shocks affecting the degradation rate is established to be proportional to the shock size. The resulting model includes some existing models as its special cases and can easily be extended to cases where the degradation process follows other random processes with independent increments. Numerical examples are presented to illustrate the applications of the proposed model. Sensitivity analysis and validation of the two-stage parameter estimation approach are conducted based on the simulation.