Abstract: By establishing the relationship between the failure rates before and after preventive maintenances, this paper gives a nonlinear constrained model of equipment preventive maintenance strategy.The model aims to minimize the total cost of the system in a finite production time interval by synthetically considering the repair cost,preventive maintenance cost and production loss cost.It is solved by making use of the global search ability of genetic algorithm and the local search ability of nonlinear programming.A numerical example shows that the combination of the genetic algorithm and the nonlinear programming gives faster convergence to the global optimal.

Key words: Preventive maintenance, Reliability, Failure rate, Genetic algorithm, Nonlinear programming