In this study, a combined analytical-finite element approach is proposed for vibro-acoustic computation of three-dimensional irregular cavities with constant depth in application to vehicle interior noise response problem. Through this study, the effect of cavity irregularities on panel-cavity modal coupling is analysed. The results show that more cavity modes are coupled with floor panel modes in the case of irregular cavity as compared to the case of simple regular cavity. However, the overall coupling strength of each cavity mode of the former is not necessarily higher than that of the latter. As for the prediction of AFRF, a comparison has been performed for the two cavity cases. The AFRF results of the two cases show that the simple cavity model is reasonably good for estimating the response order of magnitude and rough general trend. It has to be noted, however, that the comparison is not direct because the modal acoustic pressure distribution is quite different for both cavity cases. Therefore, it becomes very challenging to determine the response location of one cavity model that exactly corresponds to that of the other. The comparison was done for 16 points inside the cavity and it was found that the AFRF results at some frequencies are quite different in magnitude and phase as well. Consequently, the significance of irregular cavity AFRF computation is more evident when sound pressure distribution is an important concern. In tonal noise control applications, for example, the position of the attenuator, whether it is an active or reactive system, primarily depends on the location of significant pressure amplitude. In addition, the significance and advantage of the proposed approach over the direct finite element method for this type of problems are illustrated. The natural frequencies of a rectangular cavity are calculated using the proposed approach and compared with FEM and analytical results, and it is shown that the proposed approach matches well with the analytical approach. The formulation of the proposed technique makes use of the constant depth feature such that the use of the finite element is primarily to find the two-dimensional irregular shape modal properties. The overall three-dimensional modal properties are obtained by extending the finite element results using the exact analytical terms.
Vibro-acoustic computation of irregular cavities using a combined analytical-finite element approach with application to vehicle interior acoustics
Vibroakustische Berechnung unregelmäßiger Hohlräume mit Hilfe einer kombinierten analytischen und FE-Lösung mit Anwendung auf Akustik der Fahrzeuginnenräume
International Journal of Vehicle Noise and Vibration ; 8 , 2 ; 136-151
2012
16 Seiten, 8 Bilder, 1 Tabelle, 22 Quellen
Aufsatz (Zeitschrift)
Englisch
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