The Technology Of The Automobile's Surface Fairness In Computer Aided Shape Design

The application in the automobile body shape-designing with CAD(computer aided design) and non-contacted three-dimentional scanning technology is not only decrease greatly the cycle of researching the vehicle shape but also improve greatly the quality of the automobile shape sculpt . Besides, the fairness of the automobile's body has not only influence on the dynamical parameter and economic parameter but also the manufacture quality of the automobile. Therefore, the problem of fairing becomes very important in the automobile body shape-designing, it is one of the research emphases of the automobile body shape-designing software empoldered companies and the automobile companies.The commonly programme of designing the automobile body is to draw romance picture, to make model, to examine and edit model, to measure model and to construct a digital automobile's body model. Through the point data of an electrical minisize vehicle model with three-dimentional scanning measure, we research deeply the problem on improving the efficiency of constructing curve and surface. Besides, some theories and technics of curve and surface are also significative explored.(l)Both the removal or insertion of knot and the elevation or reduction of degree are used to uniform a group of curves' parameters.(2)The continuity of curve and surface are required in the fairness of curve and surface. We also give the condition and the arithmetics of the continuity of curve and surface.(3)The fairness of curve and surface must be meet the need of the production technics through the research on the fairness rule of curve and surface .This rule will provide the basis for the quantification of fairness.(4)Based on researching several arithmetics of fairing curve and surface in automobile body shape-designing. We afford a Energy optimization method which can be extended to the NURBS.(5)The process of dividing surfaces can decrease the data quantity in fairing surface with energy method.The energy optimization method in this paper can make the even fluctuation of curvature of the automobile body and the small strain energy.