The active structural acoustic control of a beam with classical boundary conditions using an active constrained layer damping and a secondary acoustic controller is investigated. The beam is placed on an infinite rigid baffle. It is excited by a plane wave acoustic load and radiates sound into an anechoic acoustic medium. The primary goal of the control mechanisms is to reduce the radiated sound in a wide frequency range.; The active constrained layer damping is used to dissipate the vibration energy of the beam. Although a damping device is usually more effective in mid- to high frequency ranges than in low frequency range, this research has developed a methodology that makes the active constrained layer damping effective in controlling resonant responses in the low frequency range. The secondary acoustic controller complements the active constrained layer damping by minimizing the subsequent radiated sound power. This acoustic controller is highly effective in reducing the overall noise in the low to mid-frequency ranges.; In conclusion, it is found that, for a tonal excitation, the combined application of the active constrained layer damping and the secondary acoustic controller is an effective means to control acoustic response of a vibrating beam. By using them together, an efficient control of radiating sound power of vibrating beams is achieved in a wide frequency range.
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