Replacement Policy for Heterogeneous Items Subject to Gamma Degradation Processes

Ji Hwan Cha, Maxim Finkelstein, Gregory Levitin

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


A hybrid preventive maintenance policy for heterogeneous degrading items is discussed. It combines the classical age-replacement strategy, when a system is replaced either on failure or at the predetermined age, with replacement of the system when degradation reaches the predetermined level at some intermediate time. Items come from two subpopulations with different reliability characteristics. Non-homogeneous gamma processes model degradation of an item from each subpopulation. We justify probabilistically the superiority of the proposed policy over that for homogeneous populations and over the policy without possibility of additional replacement. The corresponding long-run cost rate is derived for the suggested cost structure. Some detailed numerical illustrations are presented and relevant sensitivity analysis for the main parameters of the model is performed.

Original languageEnglish
Pages (from-to)1323-1340
Number of pages18
JournalMethodology and Computing in Applied Probability
Issue number3
StatePublished - Sep 2022

Bibliographical note

Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.


  • Dependent increments
  • Heterogeneous degradation process
  • Hybrid preventive maintenance policy
  • Mixed gamma process
  • Probabilistic analysis


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