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The diagram shows an ultrasonic transducer stuck to the bottom of an ultrasonic cleaning tank full of water/detergent. It's not supported at the opposing end - just hanging off the bottom of the tank. The piezoelectrics vibrate, causing the compression bolt to extend/contract at around 20-40Khz typically. This vibration is transmitted through the tank to the liquid where it causes cavitation, and cleans stuff.

Since it is unsupported at the opposing end, why is this energy transmitted to the tank?

enter image description here

Oliver Walters
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1 Answers1

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The inertial mass of the transducer assembly itself furnishes the "backing" force that lets the transducer propel energy into the tank. As the transducer deflects, the deflection wave bounces off the mass of the assembly and heads away in the opposite direction- that is, into the tank instead of out the bottom of the transducer assembly.

This is called an inertially-clamped condition and is BTW the manner in which lasers are used to crush the fusion capsules inside a fusion reactor. The energy is dumped into the capsule so fast that the inertia of the capsule itself prevents the capsule from "getting out of the way".

The inertially-clamped condition (also known as the mass-controlled regime) can be mathematically modeled and used in design. For example, if an anvil is a certain amount heavier than the hammer head striking it, then very little of the hammer's velocity gets transferred to the anvil, which just sits still while the hammer head bounces off it and flies away.

niels nielsen
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