The Simplification of Cut Sequence Set Analysis for Dynamic Systems

For a dynamic fault tree (DFT) that models dynamic system, the occurrence of top event depends on not only the combination of basic events, but also on the occurrence order of basic events. Cut sequence is a set of basic events that fail in a particular order that can induce top event. Cut sequence set (CSS) model uses cut sequences to analyze the dynamic behaviors of dynamic systems, and it includes two parts: the generation and the quantification of CSS. Since the known CSS model has to face large complexity, the paper provided several simplification methods so as to decrease the computational complexity. The simplification methods include the modularization of individual sub-trees, simplifying the equation of the top event probability, ignoring the cut sequences that contain many basic events. An example is used to illustrate the applications of the simplification methods.