A preventive replacement policy based on system critical condition

The article considers a linear consecutive-k-out-of-n: F system and a linear connected-(r, s)-out-of-(m, n): F system. It is assumed that the components are identical and the failure times of components follow an exponential distribution. The system is continuously monitored and the component failure can be known at any time. A preventive maintenance policy is proposed, and it is based on the system critical condition which is related to the number of working components in the minimal cut sets of the system. If there is at least one minimal cut set which consists of only one working component, the system is maintained preventively after a certain time interval and the failed components are replaced with the new ones to prevent the system failures. The expected cost rate is used as an optimization criterion. The expected cost rate is estimated by simulation and numerical examples are studied. The numerical analyses are exploratory and not generalizable.