An improved modular approach for dynamic fault tree analysis

Modularization technique allows efficient simplification of Dynamic and Static Fault Tree (FT). Each independent sub-tree (module) in static FT can be calculated separately and substituted by a basic event with obtained probability of failure. However, there is a significant restriction of this procedure in Dynamic FT, if it is converted to a Markov Chain. An independent sub-tree inside of Dynamic FT cannot be converted to basic event in general case, because corresponding Failure Rate (FR) is not constant and is not defined at arbitrary time. In the present paper we consider a set of cases when this modularization technique is still possible inside a Dynamic FT.