Research And Application Of Computer Aided Fault Tree Analysis

Fault tree analysis(FTA), an important branch in system reliability engineering, is a common practical technique used in evaluating reliability and safety for large-complex system at home and abroad presently. Now, research and application of FTA which is based on probability and statistic has been well developed. Mostly, there is fuzzy information exist in engineering project just as fuzzy event probability, the traditional FTA couldn't deal with such system. So the fuzzy system's reliability study has become an important research in reliability engineering. Furthermore, with more large complex systems appearing, the scale of FTA turns to be hugeness, engineers are in urgent need of finding a new tool to solve this problem. The advancing computer techniques make computer to be a new reliability analyzer for FTA, and computer aided FTA becomes a new hot research in reliability engineering. In conclusion, in order to solve the system fuzzy information, to widen domains of application of FTA and to develop large-scale software for reliability, the paper do an in-depth study on these problems.In this thesis, The basic trait and step of the FTA are introduced, especially the basic theory of the qualitative analysis and the quantitative analysis. A new concept of uncertainty importance is developed. Furthermore, the author combining the FTA with the fuzzy theory to solve the uncertainty problem, and the basic trait and step of the fuzzy FTA are analyzed and compared, especially the fuzzy event probability importance. In the aspect of the selection of fuzzy probability of bottom events, the concept of using fuzzy measure to compare the fuzzy number model is brought forward. The paper compares linear fuzzy number's fuzzy measure and nonlinear fuzzy number's fuzzy measure, show the feasibility of using the probability of fuzzy number to replace the accurate probability. And the definition and arithmetic of the logic gate fuzzy arithmetic operators is established. However, the paper improve such FFTA.Based on the study of these theory, this thesis successfully develop a computer aided FTA software by using VB.NET and database technology. The software is designed under the rule of layers design and object design, using dynamic numerical method and database technology. The software has high computing speed and use less memory. It has sound ability to meet the demand of microcomputer for large-scale FTA. Several illustrative example analyzing and compare with other software proved that the software is scientific and efficient.