Modeling of geometrically complex structures for discretisation methods (FEM, BEM)

For the static analysis of complex structures (components assembled to a structure) we must have a complete geometrical representation of the real body. There are three possibilities to model a three-dimensional body - the wireframe model, the surface model and the volume model. Wireframe-Models are only composed of points and edges, without a connection between the modelled edges and the surfaces. To get a surface model you have to describe a body by its bounding surfaces. The volume model describes the shape of a body in a mathematically exact way and therefore you can get, if required for the static analysis, any information from the inside of the body. The computer-internal representation of a volume model can be archived in different ways: * Direct representation of the volume (e.g. Spatial Enumeration, Spatial Subdivision, Constructive Solid Geometry, Primitive-Instantiation, Sweeping-Model). * Indirect representation - the volume is described by surfaces with neighbourhood relationships (e.g. BRep - Boundary Representation, Triangulation). To balance the pro and cons of the different models, it is necessary to use some of these representations in a modelling system (hybrid models) simultanously. Hence, it is necessary to transform objects from one representation into another. This is not easy and sometimes it is not possible at all. For the static analysis the geometric model is sometimes insufficient. Additional information about the load and material properties as well as the building history is required. In this work an accurate data structure will be developed, and an implemention in a modelling-system for tunneling will be tested.