Metglas Acousitc Panels for Damping and Modication of Noise

Noise from machinery and other sources may be controlled passively by high transmission loss panels and damping, or actively using discrete localized sensors and actuators to cancel noise. Effective enclosures for passive noise control are often heavy, especially below 500 Hz, while active noise cancellation systems can be expensive, bulky, and difficult to adapt to different situations. Satcon proposes to develop light weight high transmission loss panels for noise control. Panels will be formed from an array of magnetostrictive Metglas sheets mounted in light weight frames (less than 1 kg/m(2)), with adjacent loops of wire terminating in an adjustable impedance. The Metglas/frame composite panel will act like a dynamic resonator, making its effective mass much greater than its actual mass. The tuning of the panel to achieve dynamic resonance simultaneously over a useful range of frequencies is accomplished by proper choice of the frequency dependence of the loop termination impedance. In principle the choice of impedance can produce any desired acoustic behavior of the panels. A sample panel will be built and demonstrated in Phase I, and a prototype system, adapted to some sound source of interest to the Army, will be built in Phase II. Testing and system design will be done with help from BBN Corporation. BENEFITS: In addition to disguising noisy military equipment to avoid detection, Metglas acoustic panels can be used wherever low weight is important enough to justify the cost, including any application where discrete active noise control (even more expensive) is now used. Applications include noise control in the interiors of aircraft, luxury cars and yachts, and protection of satellites from damage due to vibration during launch.