Optimum Periodic Component Reallocation and System Replacement Maintenance

In a repairable system with multiple functionally interchangeable components, the components may work in different environmental or operational stresses associated with their positions, and thus, experience different failure rates and nonhomogeneous degradation processes. For such a system, the system lifetime can be improved by reassigning the components among the positions in the system after a period of operation. In this sense, the component reallocation (CR) is an option of preventive maintenances. This paper studies a new maintenance policy, which performs periodic preventive system replacements and periodic preventive CRs between system replacements as well as minimal repairs for emergency failures. An optimization model is established to determine the time and assignment for CRs and the time for system replacements with the objective of minimizing expected annual system maintenance cost. The model also justifies if the CR is economically beneficial and deserved to be implemented. The proposed CR-based maintenance policy is further specified for exponential component lifetime distributions and Rayleigh lifetime distributions, and analytical results are derived. Finally, numerical examples for general Weibull lifetime distributions are presented to demonstrate the efficiency and insights of CRs in maintenance.