System reliability allocation methodology based on three-dimensional analyses

Abstract

One of the undeniable problems in the design of complex multicomponent systems is the difficulty in specifying reliability requirements of individual components in the most objective and effective manner. This paper presents a comprehensive approach for reliability allocation by comprehending functional dependency and failure criticality for each component or subsystem. It decomposes the system into three dimensions, specifically physical, functional and time, and helps identify the interrelationship between components and functions as well as single-point-failure problems. A methodology is proposed to compute overall reliability allocation index considering dependency and criticality criteria. Dependency values are calculated using the analytic hierarchy process, and the criticality values for each single-point-failure are derived from Failure Modes and Effects Analysis (FMEA) document. The methodology builds an effective link between failure analysis and reliability allocation process. A case example is presented to demonstrate the proposed approach.