Robustness of Age Replacement Strategy in Maintenance Management

The robustness problem of age replacement models in maintenance management is discussed in this paper. The characteristics of optimal solutions of age replacement models, with cost and availability objectives, are presented. A new algorithm based on the Newton method is established to calculate the optimal maintenance interval and cost rate. Comparing with the TIT (Total Time on Test) plot method, much faster calculation and better accuracy are achieved. The variation of the optimal maintenance interval and costs due to the changing of the values of certain parameters is investigated. The Weibull distribution is used as the typical distribution of product life time, and 3D and 2D plots are used to show the sensitivity to these parameters. By the sensitivity analysis, it is found that the age replacement strategy is usually robust when all the parameter values are large enough.