Convertible Car Hoods - the Problem of Form-finding and Related Aero-structure Problems

摘要

Although in existence for many decades, convertible car hoods, 'soft-tops' represent a sizeable design problem. The fabric in its tensioned state adopts a saddle shape, which is not in keeping with the general outline of the rest of the body of the car. Hence, the first (aesthetic) design requirement is to achieve a contour of the hood, which, in a fully closed state, and at varying speeds of the car, matches the styled shape of the car. The main functional requirements cover essential comfort items, such as no leaks of air or water, and, relevant to this project, response to aerodynamic loading. The work presented in this paper describes certain aspects of computational methodology aimed at complementing/eliminating expensive prototyping methods for newly designed hoods. The computational model developed for this purpose incorporates an initial stress-prediction module, followed by a load analysis module, in which fluid-structure interaction is taken into account. The proposed numerical approach is validated using small-scale models in a wind tunnel.