| Automobile panel stamping is an extremely important process for manufacture of automobile parts. Nowadays, traditional methods are still in used in panel die designing and manufacturing in domestic automobile industry. Process planning and die designing depend mainly on the experience of designers and a trial-and-error procedure is often adopted to get qualified dies. This method is inefficient, costly, time consuming, and the quality of dies can not be ensured. In this thesis, some preprocessing techniques of finite element mesh generation in automobile panel are investigated and then the independently developed CAE commercial code KMAS/Auto-meshing for sheet metal forming is moreover perfected. The researches belong to the development of CAD/CAE/CAM integration system for sheet metal stamping and die design at Institute of Automobile Body and Die Engineering, Jilin University.Finite element mesh generation is the kernel of pre-process. Mesh generator is the necessary part of CAE, it is very important for the integrality of whole system to do work in this area. The development of mesh generator can not do well without the research of CAD, because the CAD design is the input of mesh generator. According to the deep analysis of IGES and STEP, mesh generator team designed framework and data structure of mesh generator based on B-Rep. The foundation of this framework is the topology relation of geometry, including surface, surface surround box, surface border, curve, element, element edge and node. As a result, this framework can link CAD data and CAE mesh data into an organic whole. Basing on the research of IGES and STEP, the data reading interface of mesh generator in KMAS has been developed. This interface can read CAD data credibly into the mesh generator, and including data repair module in reading process. By using this module, mesh generator can analyze CAD file, find semantic error and failure information, and repair them while transform the CAD model.Some bad complexions will come out in read CAD data, for instance, furl in border, edge repeat, and different aperture and so on. The veracity of result will be blocked deeply by CAD data, even if the direct CAE analysis can be performed without necessary data repair. It is necessary for engineers to repair the mesh of CAD design in order to get the correct result sometimes. Mesh repair is a very difficult and time-consume process. In this paper, CAD design repair in sheet metal mesh generation is researched from CAD point of view. The CAD data repair module of mesh generator is developed according to modularization idea, including initialization, pre-process, geometry simplification, stitching, geometry building, and post-process. The data disrepair led by tolerance will occur when the data is transformed between different CAD systems. In this paper, tolerance problem is investigated in-depth, alterable tolerance of data repair module is defined in the round. The tolerance regulation is the foundation of data repair, and geometry simplification, stitching and building which base on the geometry analysis are the kernel. The modularized data repair method is the research for engineering application, not simple program; as a result, it is integrated in the KMAS system well.In this thesis, three important problems are investigated aiming at automobile panel stamping analysis: consistency of surface normal direction, erasion of processing hole and T-connectivity. Three kinds of CAD-based automatic treatment arithmetic are put forward for the first time. By using these three methods, the whole quality of automobile panel mesh is enhanced greatly; the efficiency of KMAS pre-process is improved.Because the adjustment of mesh normal direction has a low efficiency and precision, the treatment is put in front of mesh generation in this paper. The normal directions of adjacent surfaces are decided by the adjustment of normal directions in the common points of adjacent surfaces.The basic of automatic removing holes is the classified definition of...
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