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As we continue to create ever-lighter road vehicles, the challenge of balancing weight reduction and structural performance also continues. One of the key parts this occurs on is the hood, where lighter materials (e.g. aluminum) have been used. However, the aerodynamic loads, such as hood lift, are essentially unchanged and are driven by the front fascia and front grille size and styling shape. This paper outlines a combination CFD/FEA prediction method for hood deflection performance at high speeds, by using the surface pressures as boundary conditions for a FEA linear static deflection analysis. Additionally, custom post-processing methods were developed to enhance flow analysis and understanding. This enabled the modification of existing test methods to further improve accuracy to real world conditions. The application of these analytical methods and their correlation with experimental results are discussed in this paper.

Wind noise consistently ranks as one of the most influential factors with respect to perceived vehicle quality. In an effort to address this issue we investigated building, solving, and analyzing a CFD (Computational Fluid Dynamics) wind noise model using LES (Large Eddy Simulation) turbulence modeling. An experimental and numerical study of the effect of an actual sunroof deflector that was in place or removed from the vehicle was conducted. The combined effects of a relatively small mesh size and time step to capture the transient flow phenomena and a large number of time steps to insure valid comparisons with typical experimental results, led to extremely large solution times and a subsequent large amount of data to analyze. While good results were obtained, the practical use of this type of analysis in a development timeline was determined to be limited.

Unsteady flow over automotive side-view mirrors may cause flow-induced vibrations of the mirror assembly which can result in blurred rear-view images, adversely affecting marketability through customer comfort and quality perception. Prior research has identified two mechanisms by which aerodynamically induced vibrations are introduced in the mirror. The first mechanism is unsteady pressure loading on the mirror face due to the unsteady wake, causing direct vibration of the mirror glass. The second mechanism, and the focus of this study, is a fluctuating loading on the mirror housing caused by an unsteady separation zone on the outer portion of the housing. A time-dependent Computational Fluid Dynamics (CFD) methodology was developed to correctly model mirror wake behavior, and thereby predict flow-induced mirror vibration to improve performance estimations.