Maintainability Policy for Deteriorating System with Inspection and Common Cause Failure

A condition based on preventive and corrective maintenance policy is proposed for a continuously operating system. The condition of the system is assumed to deteriorate with time. The model incorporates both deterioration as well as random common cause failures. The deterioration stages are modeled as discrete state processes. The system is put to random inspection to know the condition. The mean times between inspections are exponentially distributed. If the observed condition at an inspection exceeds the threshold (N) deterioration level, the preventive maintenance (PM) is performed, else no action is taken and the system continues to run. The proposed model considers an accumulated deterioration based on increasing intensity for the random failures. The transient solutions using Laplace transform as well as steady state solutions using recursive technique are suggested to compute the state probabilities of the system. Various reliability measures of the system have been established and validated numerically by taking an illustration.