Optimal design of a repairable k-out-of-n system considering maintenance

The configuration of a repairable system directly affects its performance measures such as mean time between failures and steady state availability. Corrective, preventive, and condition-based maintenance strategies can also affect the overall performance of the system. The objective of this work is to investigate the possible trade-off between the configuration of a repairable k-out-of-n:G system and its maintenance strategy. The redundancy (the number of active redundant components) and the number of cold standby components are considered to be the design decision variables, whereas the repair capacity and the maintenance activation point are considered to be the maintenance decision variables. The corresponding stochastic process for this model is formulated using the continuous time Markov process; as well an optimization model is introduced for cost-effective design of a repairable k-out-of-n:G system. The optimization model is used to minimize the overall operational and maintenance cost associated with the system, considering constraints on availability, space and/or budget. Finally, genetic algorithm is used to find the optimal values for the decision variables. The result is demonstrated using a numerical example.