Bus Body Computer Aided Design Based On UG

The development level of a nation economy has important relationship with the development level of the country automobile industry. America, Japan, Germany, Korea, Italy are the good proofs. The rich big economic countries of the world are closely related with the car industry. New technique of car design has got further development in drastic market competition. Car body CAD(Computer Aided Design) was begin with the end of twenty century , it is the infallible result of computer apply, it has improved the traditional way of car body design, it is a proof of productivity gets further development. CAD can faster the course of automobile design and exploitation, easy modify body' s parameter and data management, shorter research term and lower cost. Adoption virtual CAD mostly concentrates the sight effect,virtual design and virtual assembly.At first, the thesis tells us present development condition of automobile CAD at domestic and international situation and its aim and denotation. To current circumstance, our country has so large distance between with international famous automobile designing and making companies, not only in car body but also shape design. CAD is infallible tendency in the field of automobile design because the way can shorter the time of design and lower cost. The second, the thesis introduce the principle of NURBS curve and evaluating index of the curve quality. The thesis takes the design of the bus body shape and frame as an example, provide computer aided design way of three-dimension, its main content include three-dimension modeling and model decorating. In this segment, a design method basis on Unigraphics is presented for bus body in accordance with the demand of the factory. It utilizes UG and 3dmax to design without object models for several selected proprietary bus, then choices the best one and utilizes UG to design without any object models, then conform the target parameters,laying-out,chair size and so on. In course of designing the bus body shape, applying the UG software which includes the shape design way of NURBS free curve, designing the main profile-line of the bus body shape, after editing the shape line, sweeping the curve lines to get body shape, then designing inner decoration, including panel, carpet, chairs, ceiling and flank and so on. Then designing the bus body frame which comprises six parts and virtual assembly the six parts, checking the effect and amending the insufficiencies. Do the same work in assembling the parts between frame and surface. After that, applying some relevant softwares to do same post- transacts. Finally, introduces prospect and summarize the thesis.