Abstract
Multi-state systems (MSSs) are common in real-word applications, in which a system and/or its components exhibit multiple stochastically-dependent states or performance levels. Such characteristic poses challenges to the reliability evaluation of MSSs. Multi-valued decision diagrams (MDDs) have been developed to address the reliability analysis of MSSs under the assumption that the failure-time parameters of system components are deterministic. However, due to epistemic uncertainty, it is often difficult or impossible to obtain the determinate values of the component parameters. Therefore, this paper aims to address the MDD-based reliability evaluation of MSSs with epistemic uncertainty by incorporating the interval theory and fuzzy set theory. The proposed methods are verified through a detailed case study of a high-speed train bogie system. The results show that the proposed methods can obtain practical reliability evaluation results reflecting the condition of epistemic uncertainty.