Search Results

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.

Layered materials are one of the most commonly used acoustical treatments in the automotive industry, and have gained increased attention, especially owing to the popularity of electric vehicles. Here, a method to model and couple layered systems with various layer types (i.e., poro-elastic layers, solid-elastic layers, stiff panels, and fluid layers) is derived that makes it possible to stably predict their acoustical properties. In contrast with most existing methods, in which an equation system is constructed for the whole structure, the present method involves only the topmost layer and its boundary conditions at two interfaces at a time, which are further simplified into an equivalent interface. As a result, for a multi-layered system, the proposed method splits a complicated system into several smaller systems and so becomes computationally less expensive.