The Reverse Modeling Of The Automobile Front Fender And Its Deep-drawing Simulation

There are several defects about the design methods of automobile panels, such as the long design cycle, the low precision and the bad exchangeability. In this dissertation, the automobile front fender modeling is studied in combination with numerical simulation techniques of sheet metal forming process and reverse engineering techniques. The analysis of the front fender forming process is also discussed on the basis of considering the geometry feature, material properties and the characteristics of its forming process synthetically. The purpose is conducted to develop the reverse design technique of automobile panels, analyze the deformation process of the front fender, and provide a new design approach for the design of typical vehicle cover panels.Firstly, the background, purpose and actuality at home and abroad of the research are illustrated, and the geometric and forming characters of the front fender are analyzed according the fender size, material, shapes and so on.Secondly, the data sampling and processing technology of the front fender in reverse engineering are researched. The contents involve data collection and data processing. The latter includes filling, denoising, condensing, smoothing, detaching and outputting point clouds.Thirdly, the model reconstruction technique of the front fender is discussed. After introducing the theories for curved surface reconstruction, the parametric surface fitting method of rectangular domain is employed for the surface reconstruction of front fender. Then the surface smoothness and the model accuracy are evaluated for the continuous work. The main work focuses on the technology of clouds data partition, point clouds data processing of the front fender, the surface construction of fender model and the evaluation model smoothness and accuracy.Next, the fender model is imported into sheet forming simulation software after the surface reconstruction. After checking the surface meshes closeness and designing the binder surface and addendum surface, the punch -die shapes are obtained. Setting the rational boundary conditions and adopting FEM theory perform the forming process simulation program of the front fender. In the phase of post process, the process improvement proposals are put forward aiming at the settlement for the possible defects. So the model constructed by means of reverse theory may be transformed to the eligible product. The simulation results can be fed back for product and die optimum design. The results of this paper show thataberration phenomena occur in the regions of sewing surfaces, because those surfaces may be of disfigurement after meshing. We propose an ameliorated surface reconstruction scheme. It can avoid these defects, and good results are achieved.Finally, the summary and overview for future research are put forward.The approach proposed by this dissertation combines reverse engineering techniques and CAE techniques. It can be used for the design optimization and manufacturing of typical automobile panels in order to get a new structure product. The design results are different from the original product. This design mode can be used for product innovative design, and can shorten the development cycle and reduces the cost at the same time.