Resilience improvement of a critical infrastructure via optimal replacement and reordering of critical components

One of the most important obstacles in improving the resilience of critical infrastructures is the timely replacement of critical components. However, the shortage of spare parts often keeps practitioners from achieving this goal. Moreover, it is common that spare parts may deteriorate on the shelf. In this paper, we focus on a one-component deteriorating system carrying one deteriorating spare part. Both failure-switching and preventive-switching strategies are considered for component replacement during each operating cycle to minimize the long-run cost rates. A case study on gearbox replacements for an offshore wind farm is provided to illustrate the proposed joint component replacement and reordering policies in improving the resilience of critical infrastructures. Although the chance of failure of such a system may be reduced by the preventive-switching strategy, the failure-switching strategy may still result in better economic performance due to the on-shelf deterioration and salvage of spare parts. Abbreviations: CDF: cumulativedistributionfunction; PDF: probabilitydensityfunction; PR: preventivereplacement; CE: cumulativeexposure.