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Near-field structure-borne sound holography for finite plates
A concept for the inverse reconstruction of a structure-borne sound field is examined, following the basic priciple behind Near-Field Acoustic Holography. Considering a finite isotropic plate subjected to normal excitation, a limited number of structural response measurements can be used to continuously extrapolate the resulting bending wave field. The holographic procedure is based on seeking a solution to the corresponding bending wave equation in polar coordinates. The required boundary conditions can be obtained by sampling the structural response of the plate along circle lines, in the near-field of the excitation and close to the edges, therefore taking into account outgoing and reflected waves. In this paper the theoretical basis for the concept and its application to finite plate structures is considered. It is investigated numerically, by simulating the case of an all-around simply supported plate driven by a set of arbitrary point forces. The possibility of implementing a procedure reminiscent of Near-Reid Acoustic Holography in a structure-borne sound scenario has been presented and verified through numerical simulations. If normal forces are assumed, the continuous bending wave field of a finite plate can be reconstructed based on a finite number of response measurements. Due to the dependence on a polar coordinate system, reconstruction on a rectangular plate is confined to an annular area, which is an inherent disadvantage. Obviously this is more limiting for plates with high aspect ratios, but even for a square plate the wave field near the corners cannot be reconstructed. It will therefore be necessary to investigate how this procedure can be applied in cartesian coordinates, in order to expand the reconstructable field area.
Near-field structure-borne sound holography for finite plates
A concept for the inverse reconstruction of a structure-borne sound field is examined, following the basic priciple behind Near-Field Acoustic Holography. Considering a finite isotropic plate subjected to normal excitation, a limited number of structural response measurements can be used to continuously extrapolate the resulting bending wave field. The holographic procedure is based on seeking a solution to the corresponding bending wave equation in polar coordinates. The required boundary conditions can be obtained by sampling the structural response of the plate along circle lines, in the near-field of the excitation and close to the edges, therefore taking into account outgoing and reflected waves. In this paper the theoretical basis for the concept and its application to finite plate structures is considered. It is investigated numerically, by simulating the case of an all-around simply supported plate driven by a set of arbitrary point forces. The possibility of implementing a procedure reminiscent of Near-Reid Acoustic Holography in a structure-borne sound scenario has been presented and verified through numerical simulations. If normal forces are assumed, the continuous bending wave field of a finite plate can be reconstructed based on a finite number of response measurements. Due to the dependence on a polar coordinate system, reconstruction on a rectangular plate is confined to an annular area, which is an inherent disadvantage. Obviously this is more limiting for plates with high aspect ratios, but even for a square plate the wave field near the corners cannot be reconstructed. It will therefore be necessary to investigate how this procedure can be applied in cartesian coordinates, in order to expand the reconstructable field area.
Near-field structure-borne sound holography for finite plates
Greussing, Dietmar (author)
2012
6 Seiten, 4 Bilder, 1 Tabelle, 5 Quellen
Conference paper
English
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