Reliability importance of components in a complex system

Reliability importance indices are valuable in establishing direction and prioritization of actions related to an upgrading effort (reliability improvement) in system design, or suggesting the most efficient way to operate and maintain system status. Existing indices are calculated through analytical approaches, and application of these indices to complex repairable systems may be intractable. Complex repairable systems are being increasingly seen, and issues related to analytical system reliability and availability solutions are well known. To overcome this intractability, discrete event simulation, through the use of reliability block diagrams (RBD), is often used to obtain numerical system reliability characteristics. Traditional use of simulation results provides no easy way to compute reliability importance indices. To bridge this gap, several new reliability importance indices are proposed and defined in this paper. These indices can be directly calculated from the simulation results and their limiting values are traditional reliability importance indices. Examples are provided to illustrate the application of the proposed importance indices.