Availability optimization of systems subject to competing risk

Y. Zhu, E. A. Elsayed, H. Liao, L. Y. Chan

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


This paper considers a competing risk (degradation and sudden failure) maintenance situation. A maintenance model and a repair cost model are presented. The degradation state of the units is continuously monitored. When either the degradation level reaches a predetermined threshold or a sudden failure occurs before the unit reaches the degradation threshold level, the unit is immediately repaired (renewed) and restored to operation. The subsequent repair times increase with the number of renewals. This process is repeated until a predetermined time is reached for preventive maintenance to be performed. The optimal maintenance schedule that maximizes the unit availability subject to repair cost constraint is determined in terms of the degradation threshold level and the time to perform preventive maintenance.

Original languageEnglish (US)
Pages (from-to)781-788
Number of pages8
JournalEuropean Journal of Operational Research
Issue number3
StatePublished - May 1 2010
Externally publishedYes


  • Competing risk
  • Degradation process
  • Non-stationary renewal process
  • Preventive maintenance
  • Sudden failure

ASJC Scopus subject areas

  • Computer Science(all)
  • Modeling and Simulation
  • Management Science and Operations Research
  • Information Systems and Management


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