A novel shape-adjustable surface and its applications in car design

Abstract

In this paper, a new parameterized surface, termed SQ-Coons surface, is proposed according to the build mode of Coons patch. The surface is always interpolated to the boundary curves, and its shape details could be controlled by the shape parameters in CE-Bézier basis functions, which makes it suitable for styling design in computer aided design (CAD). In order to exert its geometric advantages in car design, a simplified body CAD template based on characteristic lines is built according to common vehicle features. The template is built entirely from SQ-Coons surfaces, so that the overall style and detail shapes could all be modified by the control points and shape parameters of each surface. By analyzing the curvature of fifty commercial car types generated through the template and various parameters, a set of methods for constraining the range of shape parameters is proposed. On this basis, as an example, the four shape parameters of the hood surface in one model are used as variables to optimize the body shape to achieve the lowest possible aerodynamic drag coefficient in computational fluid dynamics (CFD). The results show that the design method, combining the new surface and the model template, could reflect the modeling characteristics of different cars, and improve the design and scheme adjustment efficiency in the conceptual design stage.