| الوصف: |
There is a strong demand in industry for the automatic hex meshing of complex CAD models. Fully automatic methods for hex meshing have been under investigation for many years. Although significant research has been carried out, the complexity of the models that can be meshed with well-structured meshes is very restricted. Manual decomposition is still the main industrial route to achieving this, but this process involves intensive effort from the user. In this thesis, new approaches are developed which automatically decompose complex thin-walled components into regions to which hex elements can be easily applied. The approaches are an extension and improvement of the previous ideas investigated at QUB, i.e. to decompose the thin-walled components into thin sheet, long-slender and residual regions based on local geometric characteristics. This new implementation aims at a more robust, efficient and effective method to achieve the decomposition. For the thin sheet and long-slender region, novel approaches are used to decide upon the generation of the cutting faces used to decompose the model. The resulting decomposition delivers a substantial step towards automatic hex meshing for complex thin-walled geometries. By using anisotropic hex elements in these regions, a significant saving in the number of DOF can be achieved. For the residual regions, a novel equation has been proposed to determine the net number of quad mesh singularities that are required on each face. This provides a starting point for determining the necessary patterns of volume mesh singularities to create a hex mesh. It is shown that sweepable volumes can be automatically identified. Other applications such as locating the mesh singularities and concave removal in 2D are introduced, which have the potential to be extended into 3D in the future. Finally, the idea of combining the decomposition with virtual topology is presented and some benefits are discussed. |
