Improving classical optimal age-replacement policies for degrading items

Maxim Finkelstein, Ji Hwan Cha, Amy Langston

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


We consider items with observable at inspections degradation. Following an inspection, a decision is made whether to replace an item or to continue operation. When degradation is relatively small, it is cost-beneficial to continue operation and postpone the preventive maintenance. The innovative, probabilistically justified replacement policy defines the postponement in this case. It is based on comparison of the observed degradation with the specially defined reference values. Degradation is modeled by the increasing stochastic process, specifically by the Poisson counting process and by the homogeneous gamma process. Detailed illustrative numerical examples describing the main steps of the developed original methodology are provided. They also show that the proposed policy can result in a significant cost reduction and increase in the replacement times.

Original languageEnglish
Article number109303
JournalReliability Engineering and System Safety
StatePublished - Aug 2023

Bibliographical note

Funding Information:
The authors would like to thank the reviewers for helpful comments and advice. The work of the second author was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (Grant Number: 2019R1A6A1A11051177).

Publisher Copyright:
© 2023 Elsevier Ltd


  • Failure threshold
  • Gamma process
  • Inspection
  • Poison process
  • Preventive maintenance


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