Response of a Prototype Truck Hood to Transient Aerodynamic Loading

A study was performed to determine the fluid structure interaction (FSI) for a prototype truck hood for transient aerodynamic loads. The growing need to make vehicle panels lighter to enhance the fuel economy of vehicles has made hood panels more prone to deformation and vibration from aerodynamic loads. Moreover, as global pedestrian crash standards become more stringent to provide safer front end designs to minimize injuries to head and leg, automotive manufacturers are being required to design flexible hoods that crush significantly more than the present designs to absorb the crash energy better. These flexible designs lead to potentially undesirable deformations and/or vibration behavior of the hood at typical highway speeds. This paper presents a methodology for performing fluid structure interaction computations for a typical hood by detailing the process of computing dynamic (time varying) aerodynamic loads using CFD and related deformations of the hood using commercial structural solvers. The Lattice Boltzmann Method (LBM) was employed for performing transient Computational Fluid Dynamics analysis, and commercial finite element analysis (FEA) software was used for structural calculations. The coupling between the two codes, which is described in the paper, was achieved using proprietary in-house tools. The paper identifies the wind loading conditions that have significant potential to induce hood vibration by studying “disturbed” wind profiles such as those caused by high speed wakes, high speed travel at substantial yaw angles, and wind gusts. This work demonstrates the benefits of the inherent unsteady flow field computational capability of LBM in determining the dynamic structural response to aerodynamic excitation.