Research And Application Of Modern Vehicle Body Design Method Based On Reverse Engineering

The traditional development process of automotive body is shown as following order: conceptual design, detailed design, process planning, fixture and jig design, and then manufacturing and assembly. However, at present in the production of the entire vehicles and parts, the primitive models do not come from design concept but from practical objects (clay models). Being different from the traditional process of design and manufacture, reverse engineering (RE) CAD/CAM system digitizes firstly the object by advanced measuring methods, then reconstructs the CAD model of the entity using special surface reconstruction software and CAD software, at last produces the final product or prototype according to the traditional produce process. The automotive body RE generally composed of 3D surface digitalization, data processing, surface reconstruction, CAD 3D modeling and rapid manufacture, etc. is an important method to digitize the automotive body models or other models. The digital automotive body model obtained by reverse engineering can be easily applied to body structure design, rigidity analysis, body mould manufacture, etc. and greatly shorten the vehicle body development time.The task of this thesis originates from T100 (for light duty truck), S100 (for SUV) TD001 (for heavy duty truck) and A200 (for off-road vehicle) projects of Jasmin International Auto R&D (Beijing) CO.,LTD. Using the facilities of these projects and considering the application of RE in automotive industry as the background, the thesis proposes a relatively integrated and applied modern design method of automotive body vehicle, which integrates the laser 3D measurement, CAD/CAM system, rapid prototype (RP) making, numerical control and so on.The research and development work of this thesis includes the following items:The thesis analyses the influence factors in each stage of the design and development process of vehicle body. On the basis of comparing with the design process of automotive body both domestic and abroad, the thesis presents a set of relatively integrated and applied design process and method of automotive body based on reverse engineering.The thesis deeply researches the key technologies of the reverse engineering and the methods and strategies of measuring free surface. The thesis emphatically analyses the laser 3D digitizing technology. At the same time, the basic pretreatment method for measured data is also analyzed in the thesis.Based on the deep analysis and research on the reconstruction ways for automotive body A surface, the paper summarizes up a set of methods to reconstruct free-surface model of automotive body directly by cloud data with existing software..At last, after analyzing the major influence factors on the smoothness and similarity of the body surface construction, a smooth and precise CAD model of the SUV body surface of S100 project has been reconstructed by using both theoretic analysis and optimizing means.The research results of the thesis have successfully applied in the development of above projects in Jasmin.some products of which have been put into production and market.