Calculation of the System Unavailability Measures of Component Importance Using the D2T2 Methodology of Fault Tree Analysis

Andrews, John; Lunt, Sally

Abstract

A recent development in Fault Tree Analysis (FTA), known as Dynamic and Dependent Tree Theory (D2T2), accounts for dependencies between the basic events, making FTA more powerful. The method uses an integrated combination of Binary Decision Diagrams (BDDs), Stochastic Petri Nets (SPN) and Markov models. Current algorithms enable the prediction of the system failure probability and failure frequency. This paper proposes methods which extend the current capability of the D2T2 framework to calculate component importance measures. Birnbaum’s measure of importance, the Criticality measure of importance, the Risk Achievement Worth (RAW) measure of importance and the Risk Reduction Worth (RRW) measure of importance are considered. This adds a vital ability to the framework, enabling the influence that components have on system failure to be determined and the most effective means of improving system performance to be identified. The algorithms for calculating each measure of importance are described and demonstrated using a pressure vessel cooling system.

Citation

Andrews, J., & Lunt, S. (2024). Calculation of the System Unavailability Measures of Component Importance Using the D2T2 Methodology of Fault Tree Analysis. Mathematics, 12(2), Article 292. https://doi.org/10.3390/math12020292

• Journal Article Type: Article
• Acceptance Date: Jan 8, 2024
• Online Publication Date: Jan 16, 2024
• Publication Date: 2024-01
• Deposit Date: Jan 10, 2024
• Publicly Available Date: Jan 10, 2024
• Journal: Mathematics
• Electronic ISSN: 2227-7390
• Publisher: MDPI
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Issue: 2
• Article Number: 292
• DOI: https://doi.org/10.3390/math12020292
• Keywords: System failure modelling; Dependent failures; System unavailability assessment; Dynamic and Dependent tree theory
• Public URL: https://nottingham-repository.worktribe.com/output/29549246
• Publisher URL: https://www.mdpi.com/2227-7390/12/2/292