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How to make 1 mm ultrasonic amplitude !?

Hello for all !

There is one theoretical and, could be, practical problem:

If the (30 Khz/50 W) magnetostrictive ultrasonic acuator oscillate 5 microns, and we want to increase amlitude to 1000 microns with steel sonotrode amplifier, what is the best way to do it ?
Suppose the diameter stepped snotrode amplifier have diameter ratio 2:1 (max. 4x amplification). Then, we could make 4 steps section with 4 steps of the sonotrode. If the calculation : 4x5 microns=20, 4x20=80, 4x80=320, 4x320=1280 microns ! Is it possible in practice ? Is there too much stress and loss ?

It could be very nice polich tool or kind of ultrasonc drill !?

Bane

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Hello Bane,

1 mm amplitude at 30kHz - now that would be something to see!

Sadly I don't think it's possible with current materials. There could be some way to get around the power losses (ie. supply much more power than the 50W you mention!) but stress is unavoidable. Using the [url=www.powerultrasonics.com/sonotrode_calculator.html]sonotrode calculator[/url] even for a straight rod I get 1338 MPa stress in aluminium or 2118 MPa in titanium - enough to yield any of the regular alloys instantly (in practice much less amplitude would cause fatigue fracture in only a few cycles).

I wonder if anyone's working on metal-matrix composites for power ultrasonic applications. I remember some of the ceramic-whisker reinforced aluminium materials having fantastic strength-to-weight ratios. But of course you'd need a very good financial case for going to such exotic materials. I'd love to hear from anyone with relevant information.

Bane, thanks for bringing up the topic. Maybe one day it will happen...