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Proceedings Paper

Matrix method for analyzing structural-acoustic power efficiency
Author(s): Renfang Cao; Donald J. Leo
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Paper Abstract

This paper describes a general technique to analyze the radiation impedance and actuator power efficiency of an active structure. Using a modal expansion of the structural vibration, the sound power is conveniently expressed as an integration over the surface of the planar structure. Integrating the finite element analysis into the numerical integral makes this technique applicable to any complex geometrical planar structure under arbitrary boundary conditions. As an example, this technique is applied to study of an actuator driving circular plate with an elastic support, which could be used to simulate a rigid piston. The radiation impedance and power efficiency of this active structure are studied using eigenvalue decomposition. Using general eigenvalue decomposition, the efficiency of air acoustic arrays are also analyzed. A dynamic model of the actuator is introduced to above studies by taking into account the coupling of the actuator and its host structure. Numerical results demonstrate that the radiation impedance of rigid-body motion is comparable to the analytical solution of a baffled rigid piston. Power efficiency studies demonstrate that one or two actuators will generate high efficiency when the rigid- body modes are dominant and more actuators are needed to improve the efficiency if the flexible modes are dominant. The efficiency is related to the structure impedance. A relatively soft actuator will generate a higher efficiency at low frequencies and low efficiency at higher frequencies. In contrast, a relatively stiff actuator will have a moderate efficiency at higher frequencies.

Paper Details

Date Published: 4 June 1999
PDF: 12 pages
Proc. SPIE 3667, Smart Structures and Materials 1999: Mathematics and Control in Smart Structures, (4 June 1999); doi: 10.1117/12.350100
Show Author Affiliations
Renfang Cao, Virginia Polytechnic Institute and State Univ. (United States)
Donald J. Leo, Virginia Polytechnic Institute and State Univ. (United States)

Published in SPIE Proceedings Vol. 3667:
Smart Structures and Materials 1999: Mathematics and Control in Smart Structures
Vasundara V. Varadan, Editor(s)

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