An Extended Sequential Imperfect Preventive Maintenance Model with Improvement Factors

Abstract

This article presents a generalization of the imperfect sequential preventive maintenance (PM) policy with minimal repair. As failures occur, the system experiences one of two types of failures: a Type-I failure (minor), rectified by a minimal repair; or a Type-II failure (catastrophic) that calls for an unplanned maintenance. In each maintenance period, the system is maintained following the occurrence of a Type-II failure or at age, whichever takes place first. At the Nth maintenance, the system is replaced rather than maintained. The imperfect PM model adopted in this study incorporates with improvement factors in the hazard-rate function. Taking age-dependent minimal repair costs into consideration, the objective consists of finding the optimal PM and replacement schedule that minimize the expected cost per unit time over an infinite time-horizon.

Keywords:

• Improvement factor
• Minimal repair
• Optimization
• Preventive maintenance
• Replacement policy

Mathematics Subject Classification:

• Primary 60K05
• Secondary 90B25, 62N05

Acknowledgments

The authors would like to thank the referees for their insightful comments and suggestions, which greatly enhanced the clarity of the article. All of the suggestions were incorporated directly in the text. This research was supported by the National Science Council of Taiwan, ROC, under Grant No. NSC 97-2221-E-126-011-MY3.

Notes

c _O  = 5, c _R  = c _B  = c _∞ = 15, α = 2, β = 2, h _i (t) = c _i , q _i  = q ⁱ ,, i = 1, 2,…, N, j = 1, 2,…, N − 1, k = 1, 2, 3.