Fault Tree Representation and Evaluation
Richard Saucier · 2003
In order to conduct a vulnerability analysis of a combat vehicle, it is first necessary to perform a criticality analysis, which consists of describing each of its combat functions along with the underlying systems, subsystems, and components required to support the function. The basic building blocks for carrying out this process are the fault trees; they depict the logical arrangement of the components required for the proper functioning of the vehicle. This report describes a method of representing fault trees in XML (Extensible Markup Language) and is accomplished by first defining a Fault Tree Markup Language (FTML) that can be used to describe the essential logical structure of any fault tree. Once the fault tree is described in FTML, it can then be stored as an ordinary text file. Furthermore, software described in this report will then enable one to generate both the deactivation diagram and the C code that is used to evaluate the fault tree. Fault tree evaluation means the determination of whether the system that the fault tree represents is either functional or nonfunctional, given that one or more components are dysfunctional. The second part of this report describes two methods for evaluating fault trees-one based on Monte Carlo sampling and the other on the algebra of probability theory.