Kill tree analysis method and CAD tool for aircraft complex system vulnerability assessment and safety design

In vulnerability assessment of aircraft complex systems subjected to traditional weapons, kill tree is used as a visual illustration of the critical components and all component redundancies. This research applies fault tree analysis method in reliability field to analyze the kill tree and determine the minimal cut sets for different kill levels, such as KK, K, A, B and C attrition kill. The tree is first translated to its equivalent Boolean equations and then the top-down substitution method is used. Two Boolean laws, the distributive law and the law of absorption, are used to remove the redundancies. In addition, a CAD tool based on the simple constructs (parallel, series, k-out-of-n) is developed to facilitate the analyzers to identify the contributions of critical component kill to aircraft system kill. A hypothesis aircraft complex system composed of several non-redundant components and several sets of redundant components is used as an example to illustrate the feasibility of the method and the developed tool.