Fuzzy Dynamic Fault Tree Analysis of Hydraulic System of CNC Machining Center

Fault tree analysis (FTA), as an effective reliability assessment tool, is a widely used in analyzing the risk and reliability of large scale and complex engineering systems. Dynamic fault tree analysis (DFTA) extends the static fault tree by defining additional gates to model the complicated interactions, and in most case, Markov models can be used to solve dynamic gates. In many real systems, it is quite difficult to evaluate the probability of failure events preciously due to many uncertainty factors. To account for the uncertainty resulting from the lack of sufficient data or the subjective adjustments from experts, a fuzzy dynamic fault tree model is proposed to assess the system reliability when acquiring precious probability of failure event is impossible. With the aim of obtaining the membership function of the fuzzy probability of the top event, the extension principle is employed. The proposed method and algorithm are demonstrated by a case study of the hydraulic system of a specific CNC machining center.