On optimal life extension for degrading systems

We consider life extension models for critical, complex systems with relatively long lifecycles. In contrast to traditional optimal preventive maintenance that usually minimizes the corresponding long run cost rate, a finite number of preventive maintenances are performed to increase the expected lifetime of these systems in an optimal way. The cases of periodic and aperiodic preventive maintenance actions are discussed. The proposed novel approach to life extension allows for simple sensitivity analysis with respect to parameters of the model. The obtained optimal solutions can result in a noticeable increase in the useful life of complex systems. Our findings are illustrated by numerical examples.