Estimating Multi-Phase Life Cycle Reliability by Combining Failure Rate Adjustments into Duty Cycle

Abstract

Traditionally, calculating the life cycle reliability of a system across multiple phases would be obtained by calculating the reliability of the components and the system in each phase independently, and then combining those individual phase reliabilities into an overall life cycle reliability. This paper showcases the usage of the duty cycle to combine all failure rate adjustments, e.g. environments, dormancy etc., and life cycle phases to remove the need to calculate individual failure rates for components and simplify the Reliability Block Diagram (RBD) for the system. This methodology allows an analytical reliability approach on a multi-phased life cycle using an analytical RBD as opposed to a phase-based simulation RBD. A comparison of the results between the methodologies, for a system that has a multi-phase life cycle, confirms that combining multiple factors into the duty cycle(s) allows for the use of an analytical RBD as an alternate to a phase-based simulation RBD, with the limitation that the failure rate is constant in each phase of the life cycle.