ABSTRACT
A system subject to an accumulative deterioration and continuously monitored is considered. The system fails when its degradation level exceeds a predetermined failure threshold. At system failure, a signal is sent to the maintenance team, which arrives after a fixed delay and performs an instantaneous replacement. To prevent failures and shorten the down period, a condition-based maintenance strategy is applied and the maintenance team is preventively called when the degradation of the system exceeds a predetermined preventive threshold lower than the failure threshold, with the same fixed delay for the team’s arrival otherwise. At maintenance time, an instantaneous but imperfect repair is performed. Two different imperfect repair models are considered, in the spirit of virtual age models for recurrent events. The first model assumes that the repair reduces the degradation of the system (Model I). The second model assumes that the repair reduces the age of the system (Model II). For both models, Markov renewal equations are obtained for some reliability indicators. Numerical examples are given to illustrate the analytical results and to compare both models of repair.
