A maintenance model for High Speed Train wheel subject to internal degradation and external shocks

This paper develops a condition-based maintenance model for High Speed Train wheel subject to two competing failure causes, i.e., internal degradation and external shocks that are dependent. The system fails when the degradation level or the cumulative shock damage level reaches their corresponding thresholds, which occurs first. Each shock will increase the rate of degradation by a fixed percentage, while the damage threshold is reduced when the degradation level exceeds a threshold that is smaller than the failure threshold. The system is inspected periodically to measure its degradation and damage level, and it is replaced immediately once found failed. The aim of this paper is to seek the optimal periodic inspection internal such that the expected cost per unit time is minimized. A numerical example is given to validate the model.