February 16, 2007 In an interesting development, the same technology that is used in noise-cancelling headphones (roughly speaking) is to be applied to heavy marine engines to reduce their noise and vibrations. The vibrations from marine diesels spreads through the entire hull, but researchers have now found a way of blocking the sound immediately below the engine with the help of computer-controlled counter-vibrations from an active damper between the engine and the bearing by which the engine is attached to the hull. This active bearing is made primarily from piezo-ceramics, materials that can change their shape when electrically stimulated. If they are stimulated very quickly, they generate high-frequency vibrations – which are exactly what marine engines need. Using sophisticated sensors, the scientists measure the engine’s vibrations and trigger the piezo-ceramics such that they precisely counteract this motion.
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