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The damping effect that is observed when a fibrous acoustical treatment is applied to a thin metal panel typical of automotive structures has been modeled by using three independent techniques. In the first two methods the fibrous treatment was modeled by using the limp frame formulation proposed by Bolton et al., while the third method makes use of a general poro-elastic model based on the Biot theory. All three methods have been found to provide consistent predictions that are in excellent agreement with one another. An examination of the numerical results shows that the structural damping effect results primarily from the suppression of the nearfield acoustical motion within the fibrous treatment, that motion being closely coupled with the vibration of the base panel. The observed damping effect is similar in magnitude to that provided by constrained layer dampers having the same mass per unit area as the fibrous layer.

A vehicle’s fuel mileage is directly related to its CO2 emissions, which have a negative impact on the environment. This negative vehicle attribute can, of course, be mitigated by increasing the vehicle’s fuel mileage beyond current levels: the reduction of vehicle weight is one of the options automobile manufacturers can employ to meet that goal. Similarly, an electric vehicles range can be increased by reducing the vehicle’s weight. Therefore, the minimization of the weight of vehicle sound packages while maintaining their acoustical performance has a positive impact on the environment as well as on vehicle efficiency. In this research, a simple model of a vehicle front-of-dash sound package which consists of a limp porous layer placed in series with a flexible microperforated panel is considered.

Tire/road noise has become a significant issue in the automotive industry, especially for electric vehicles. Among the various tire/road noise sources, the air-cavity mode can amplify the forces transmitted from the tire to the suspension system causing noticeable cabin noise near 200 Hz. Furthermore, when the tire is deformed by loading, the fundamental air-cavity mode separates into two acoustic modes, a fore-aft mode and vertical mode due to the break in geometrical symmetry. This is important because the two components of the split mode can increase force levels at the hub by interacting with neighboring structural modes, thus resulting in increased interior noise levels. In this research, finite element simulations of five commercial tires at rated load were performed with a view to identifying the frequency split and its interaction with structural resonances. These results have been compared with previously obtained empirical results.