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The acoustic power of a circular plate excited by non-uniform surface pressure

Szmela K., Rdzanek W. P., Rdzanek W.

Archives of Acoustics

2006

Vol. 31, No. 3

309-317

This work is focused on the analysis of the influence of a non-uniformly distributed surface excitation on sound radiation by a clamped circular plate embedded in a flat rigid baffle. It is assumed that the vibrations and radiations are axisymmetric and time-harmonic, moreover, the losses of energy into the plate's material are neglected. The influence of the surrounding medium on the vibration of the plate is not taken into account. The distribution of the exciting pressure is assumed in the form of a function whose shape can be modeled by fitting suitable values of parameters. The approximation of the distribution of the forcing pressure by the use of an analytical function makes it possible to consider practical cases. Integral formulae for describimg the active power have been obtained. The solution of the equation of motion is achieved by employing an expansion into series of eigenfunctions. An analysis of the influence of the parameters characterizing the surface excitation on the radiation power has also been presented. The low and high frequency elementary form asymptotics can be obtained by using the reached herein formulae and the known approximated expressions.

The acoustic power radiated by a circular membrane excited for vibration both by means of the edge and by external surface load

Szemela K., Rdzanek W. P., Rdzanek W.

Archives of Acoustics

2005

Vol. 30, No. 1

109-119

In this paper the acoustic power of the circular membrane, excited both by the edge and external exciting forces uniformly distributed over the whole surface, is examined. Some different amplitudes of exciting factors and some differences between the phases of excitations were considered. It has been assumed that the source of a sound is located in a flat, rigid and infinite baffle and is sourrounded by a lossless and homogeneous fluid medium. The vibrations are axisymmetric and time-harmonic. Employing the Cauchy's theorem of residues and asymptotic formulae for the Bessel functions, the asymptotes for active and reactive power consisting of elementary functions are obtained. The acoustic power radiated by the membrane was shown graphically in terms of the parameters describing both kinds of excitations.