Assessing the Reliability of a Repairable System in a Usage or Combined Time Scale

Repairable systems age with use and their failure intensities and reliability are assessed on a time scale based on their ageing. A common time scale for ageing of systems is chronological time. However, it is often seen that the same systems exhibit different failure behaviour and reliability in chronological time owing to different usages. Hence usage or a combined scale of chronological time and usage can form a better time scale to assess the reliability of a repairable system in such a case. This work presents a methodology to identify the better time scale to assess the reliability of a repairable system.