Abstract
Keywords Sensitivity, NTF, vibro-acoustic, noise, reduction
Abstract - The identification of relevant parameters for reducing a peak of noise is challenging for complex structures such as car bodies. In the low frequency range acoustic problems are dominated by structural behaviour. Often it is relatively easy to determine where the acoustic problem is and the mechanism that is responsible for it, but sometimes it is not so easy to define a feasible and realistic solution related to the structure.
Computational vibro-acoustics may bring solutions to this problem. With the extension of standard structural sensitivities to acoustic responses, the influence of any part of the vehicle can be investigated for a given peak of noise.
The working procedure developed in this project allows the identification of relevant parts in a car body for a given peak of noise at the passenger´s ears up to 200 Hz. This method takes into consideration the coupling between the fluid and the structure, obtaining, as a main result, the acoustic sensitivity of the sound pressure level (SPL) in relation to any parameter of the structure. This sensitivity shows the tendency of the SPL at any point to increase or decrease with changes in structural parameters such as mass or stiffness, and it identifies directly a possible solution to the problem.
In this work, the thickness of different panels and reinforcements was analysed. As a first step, important parts for the acoustic behaviour were found and as a second step, proposals for solution were made for the real car.
The relevant parameters obtained with this method can be used to reduce the noise inside the vehicle and improve the global acoustic behaviour at early stages of development, when the main concepts and main parts of the vehicle structure are being defined.