Reduction of interior vehicle road-noise, specifically the low-frequency 'booming noise', is an important comfort target in the development of a new car model. Structural vibrations of the car-body are often responsible for the low frequency noise, but the relationship between the interior sound level and the car body vibrations is not straightforward. This paper presents an analytical-experimental method that permits the prediction of interior sound level variations due to the local coupling of defined subsystems. The method has been derived from the substructure analysis used in structural dynamics. It has been extended to a hybrid acoustical/structural formulation, applied on a system constituted of the interior passenger cabin and the car-structure. The first analysis was performed under shaker excitation on the test-bench, where single masses were used as subsystems. The effect of mass-combinations could also be calculated. The comparison of predicted and measured sound levels at the driver's ear lead to a successful validation of the method. A road-noise analysis of a mid-size vehicle was chosen to apply and test the method under operational conditions. Under these conditions a direct determination of the transfer functions was not possible anymore and the formulation had to be adapted to the complexity of the load case, using directly the acoustical and acceleration measurements. The results confirmed the predictive quality of the method.
An analytical-experimental method for analysing the low-frequency interior acoustics of a passenger car
Analytisch-experimentelles Verfahren für die Untersuchung der Niederfrequenzakustik im Inneren eines PKW
2000
8 Seiten, 7 Bilder, 11 Quellen
Aufsatz (Konferenz)
Englisch
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