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Research Papers

Sound Radiation Control Using Multiple Adaptive Vibration Neutralizers and Hierarchical Control Schemes

[+] Author and Article Information
M. R. F. Kidner

 Vipac Engineers & Scientists, 17-19 King William Street, Kent Town, South Australia 5067, Australia

R. I. Wright

Vibration and Acoustics Laboratory, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061

J. Vib. Acoust 131(4), 041002 (Jun 05, 2009) (7 pages) doi:10.1115/1.3142867 History: Received January 31, 2007; Revised September 20, 2007; Published June 05, 2009

Adaptable vibration neutralizers (AVNs) have become common in the literature as solutions to controlling a single but variable frequency disturbance, such as the interior sound field in a turboprop aircraft. This paper presents a study of the feedback control of five AVNs to minimize tonal sound radiation from a rectangular plate with a response controlled by many modes. It is shown that the five AVNs with local feedback loops can be managed by a simple global algorithm to minimize the sound radiation from a plate. As an adaptive passive approach is used, each individual AVN can be constrained to be stable and the resulting global system is also stable. The contributions of this paper are an experimental demonstration of nongradient based control of individual AVNs, a simple hierarchical control of multiple AVNs to reduce a single global error and experimental confirmation of the physical mechanisms by which vibration neutralizers can be used to minimize noise radiation. Spatially averaged single frequency reductions of up to 22 dB are experimentally demonstrated in the radiated field.

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Copyright © 2009 by American Society of Mechanical Engineers
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Figures

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Figure 7

Input structural impedance at disturbance source location for 144 Hz test case with and without control. Solid line: converged. Dash line: no control. Dotted line: tuned.

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Figure 8

144 Hz, 2D wavenumber transforms of plate vibration. Full scale on left and focused on the sonic region on the right. Top row: no control. Middle row: tuned. Bottom row: converged. The central circle indicates the loci of the acoustic wavenumber.

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Figure 1

(a) Illustration of the effect of a tuned vibration neutralizer on a mass spring system vibrating at a frequency less than its resonance. The mobility is normalized to that without the neutralizer attached. The frequency axis is normalized to the resonant frequency of the neutralizer. Solid line: low damping. Dashed line: high damping. (b) The inertial actuator configured as an adaptive vibration neutralizer.

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Figure 2

(a) Schematic of the proposed control system showing the individual AVNs and the global simplex algorithm S and (b) simplex search operations diagram showing expansion (black star) followed by reflection (white star)

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Figure 3

(a) Test setup for single AVN and (b) cost function at 135 Hz as a function of AVN control gains normalized to its value at Ki=Kp=0. The cost function was the power spectrum of the microphone output.

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Figure 4

Experimental setup used to assess noise control using multiple AVNs

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Figure 5

(a) Average frequency response from the disturbance input force to the output voltage from the error microphones and (b) acceleration profile of the large plate at 144 Hz

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Figure 6

(a) Sum of frequency response functions from disturbance input voltage to microphone output voltage with and without control. Solid line: converged. Dash line: no control. Dotted line: tuned. (b) Convergence of cost function for 144 Hz test case.

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