1 - Risk-based reliability analysis: A powerful alternative to the traditional reliability analysis

Abstract

This chapter outlines risk-based reliability analysis. As removing a failure mode at the design stage is considerably cheaper compared to removing it at the manufacturing stage or during service, it is important that reliability is integrated early into the design of complex systems. The conventional reliability analysis is oriented towards maximizing the reliability of a system. Designers must also be able to reveal the losses from failures in order to achieve their goal. This creates the possibility to quickly filter out inappropriate design solutions associated with large losses from failures and select solutions associated with minimum losses. This chapter demonstrates, on the basis of a simple counterexample, that selecting the more reliable system does not necessarily mean selecting the system with the smaller losses from failures. Apart from estimating the losses from failures, engineers also need to specify reliability requirements regarding components and blocks in the designed systems. One of the main obstacles to developing the theoretical basis of the risk-based reliability analysis, as an alternative to the traditional reliability analysis, was the absence of appropriate models related to the losses from failures from multiple failure modes and the uncertainties associated with the probabilities with which these failure modes are activated. In order to fill this gap, models based on potential losses from failures, from multiple mutually exclusive failure modes are developed in this chapter. Models and algorithms are developed for determining the expected losses from failures for nonrepairable and repairable systems whose components are logically arranged in series and for systems with complex topology.