Roller bearings lifetime under different load conditions by a semi-Markovian approach

The key to a successful intelligent maintenance consists in replacing worn equipment before a failure occurs. In this context a predictive maintenance policy can be implemented if a degradation indicator is available. This paper focuses on mechanical equipment with degradation over time under various load conditions. More specifically, we will study the reliability of roller bearings under different load conditions. For a given state it is supposed that the failure rate is constant and proportional to the load. A semi-Markovian approach will be introduced in order to take into account failure rates due to the different operational states. Moreover this approach enables to take into account any holding sojourn time distribution