Optimal preventive maintenance for system in time-varying operation condition

A modified hybrid imperfect maintenance model (MHIM) for machine working in piecewise constant operational condition (PCOC) is proposed considering the limitation of traditional age-based hybrid imperfect maintenance model, with the assumption that failure time in different operational condition (OC) satisfies accelerated failure time model (AFTM). Method for estimating the parameters also has been provided. A policy based on optimization of average cost rate of former and current preventive maintenance intervals is presented. A numerical example is conducted to show the effectiveness of the proposed policy.