Abstract
Reduction of interior noise has become an important subject in the improvement of comfort in vehicles. A usual way of controlling high frequency noise is by adding trimmings to the interior cavity of the vehicle, but at low frequencies this is not an effective solution. Vehicles habitability limits the thickness that would be needed for noise attenuation at such frequencies.
Structure and interior air cavity design tend to be the most important working fields in controlling the acoustic response of vehicles at low frequencies. This makes it necessary to have a good mathematical model for NVH prediction in the first steps of design. This model consists mainly of two submodels: the first describes the vibrational performance of the vehicles structure and the second represents the acoustic behaviour of its interior cavity.
The accuracy of interior noise prediction at low frequency depends on the accuracy of the acoustic model and, especially, on the accuracy of the structural model. In this work, correlation techniques have been used to develop suitable structural and acoustic models and it is shown also what is the accuracy level that can be achieved in interior noise prediction.
The working procedure developed in this project allows the creation of suitable models that can be used to predict the interior noise level at any point of the vehicles cavity, such as the position of the occupants heads, before having a prototype available. As a result, engineers will be able to redesign some structural parts of the vehicle in the first design stages in order to increase the comfort level.