P. Sas, J. Von de Peer, F. Augusztinovicz

The aim of the paper is to investigate the vibro acoustic behaviour of a simple, finite, double wall structure model: a shallow, rectangular acoustical cavity composed of two parallel aluminium plates clamped to a rigid steel framework. This structure is analysed by means of analytical, numerical and experimental methods. The analytical treatment of the testing object is based on an orthogonal modal expansion of the response of the coupled acoustic-structural system. Resonance frequencies and mode shapes of the structure and of the cavity are determined. Rather than discuss the theory in details, the applied methods are shortly summarised and the physical interpretation of the results is stressed. The aim of the experiments was to verify the results of the calculations, with special emphasis on the visualisation of the sound field in the coupling cavity between the plates of the double wall model. The testing object was instrumented with a large number of accelerometers and microphones and placed in the free side of a special test box. Based on sound pressure measurements in the box and within the cavity and on vibration measurements on the enclosing plates, an extensive acoustic and structural modal test was performed. The numerical calculations are based on a coupled structural FE - acoustical BE method, carried out in three consecutive steps. The frequency response functions of the coupled system were calculated for a number of points on the plates and within the cavity. The coupling mechanism is characterised by means of participation factor calculations and the forced field in the cavity are determined by means of sound pressure mapping. The calculated and measured results are discussed in details, they are compared in tables and in figures and conclusions are drawn with special regard to the application of the applied numerical technique for Transmission Loss predictions.

DGLR/AIAA 14th Aeroacoustics Conference, 1992

Conference Paper

englisch

21,0 x 29,7 cm, 10 Seiten

DGLR-Bericht, 1992, 1992-03, DGLR/AIAA 14th Aeroacoustics Conference - Proceedings; S.561-570; 1992; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aeroacoustics

Bibliothek

1992