Reliability modelling based on dependent two-stage virtual age processes

This paper proposes reliability and maintenance models for systems suffering random shocks arriving according to a non-homogeneous Poisson process. The system degradation process include two stages: from the installation of new an initial point defect (normal stage), then that failure (defective following delay time concept. By employing virtual age method, impact external on is characterized by increment in stages, resulting corresponding two-stage When operating defective state, becomes more susceptible fatigue suffers greater aging rate. Replacement carried out either or detection state at periodic opportunistic inspections. evaluates performance investigates optimal policy. A case study cooling given verify obtained results.