Joint optimization of maintenance time and carrying spare parts for k-out-of-N system

Maintenance support of repairable warship k-out-of-N system during a task was researched. A method of how to trade off maintenance frequency, carrying spare parts and repair capacity was given. Taking the three parameters as decision variables and combined with the using and maintenance processes of k-out-of-N system, a joint optimization model of maintenance and carrying spare parts was established, in which operational availability was taken as a constraint condition and minimal maintenance costs as objective function, and repair initial condition, numbers of carrying spare parts and numbers of repair men were taken as decision variables. A modified marginal analysis algorithm was applied to solve the model through improving some drawbacks of the traditional one, and the drawbacks and corresponding improvements were also listed. Three tests were done: firstly, in order to verify the proposed model, a simulation for k-out-of-N system was implemented, and the results show that the absolute error of the proposed model is very small; second, using the optimal solution of enumeration as benchmark, performances of traditional marginal analysis algorithm and its modified algorithm were compared, and the results show that the modified algorithm has lower error and can enhance optimizing probability; third, the contribution of each modified item to marginal analysis algorithm was respectively tested.