Preventive Maintenance Cycle's Optimization of Complex System

For complex mechanical equipment containingN units the optimal model to preventive maintenance cycle policy is proposed to minimize the maintenance cost rate, the model is subject to the availability and the reliability. And optimal variable is preventive maintenance cycle. The recursion relationship of failure rate before and after imperfect preventive maintenance was built up concerning with the concept of age reduction factor. Finally, immunity particle swarm algorithm is used to solve the model; the result of an example proves the model valid and effective and the cost rate decreases 10.2% than single parts maintenance policy under identical restraint condition.