Abstract: In order to meet the need of FEM analysis for plate and shell structure, a 3D solid model is output by STL file. The model’s topology relationship is reconstructed and its surfaces are re-triangulated. On this basis elements and surfaces are classified, and valid triangle facets are chosen, and their thickness and mid-plane position are calculated. These triangle facets are carried to their middle position so that the mid-plane model of a plane and shell structure which is suited for FEM analysis is formed. This method is used to the solid models of some thin-wall structure in practice so that their mid-plane models are extracted successfully, which shows that work and analysis time for FEM models of a plate and shell structure can be reduced greatly.

Key words: FEM, Plane and shell model, Solid model, Triangle mesh