Preeti Srivastava - Department of Operational Research, University of Delhi, Delhi-۷, India
Satya Rani - Department of Operational Research, University of Delhi, Delhi-۷, India

A phased-mission system (PMS) involves several different tasks or phases that must be accomplished in sequence. The system configuration, task success criteria, and component failure characteristics may vary from phase to phase. Consequently, the reliability evaluation of PMSs is more challenging than that of single-phase in the field of system reliability analysis. The paper deals with the reliability evaluation of non-repairable Phased-Mission Systems with three phases and five phases involving dependent components in each phase.  The cumulative exposure model has been used to model a PMS, and the dependency between components of a system in a phase is modeled using the Gumbel-Hougaard copula. Reliability importance analyses of the ۳-PMS and  ۵-PMS  have also been carried out. The method developed has been illustrated using numerical examples. The proposed methodology can also be generalized to PMSs with more than five phases.

Copulas, cumulative exposure model, phased-mission system, Reliability, reliability importance measure