Algorithm study on geometric description of aircraft for vulnerability assessment based on finite element model

Based on finite element model of aircraft, an algorithm called shot line scan method, which provides the geometric description for vulnerability assessment, is proposed. The preparation of the original model of our algorithm, approximated by a series of cylinder, sphere, and cube segments, or by reading quadrilateral finite elements from some previous finite element data file (*.dat or *.bdf), has reduced the time of building models. The algorithm lays a grid with changeable grid cell size over each component and generates a shot line in each grid cell. The coordinates of intersection point of shot line and each quadrilateral finite element in the overlapping area are recorded to determine the masking/shielding for components. The number of grid cells on the component is counted and multiplied by the grid cell area to determine its presented area, which includes overlapping area from any aspect. When the shot line intersects the component, the algorithm has the ability of automatically recording the component's name, material, thickness and some useful data for vulnerability assessment. The proposed algorithm has been programmed to offer sufficient amount of detailed target description, and application shows that it can deal with many times of overlappings among components and the error can be controlled to within 5%.