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Can sound waves cause a burning effect on some materials?

  1. Aug 7, 2017 #1
    Hi, I wonder
    is it possible sound wave heat material that high that the material goes up in flames?
    Or what other type of frequency can make some materials burn?
     
  2. jcsd
  3. Aug 7, 2017 #2
    The answer is certainly "yes". It's just a question on coming up with realistic examples.
    Certainly shock waves can be used to detonate any chemical explosive.

    For normal sound waves to affect a material that way, you would need the material to absorb more energy that it can reradiate at the kindling temperature and while still maintaining contact with an oxidant.
    The volume of the sound will contribute directly to the rate of heating. If it's loud enough to make the material "rattle", all the better. The material itself should be well-insulted, to retain the heat.

    And pick a combustible material that does not efficiently reflect or conduct the sound. Perhaps a powder - or a mixture of powders with widely varying specific gravities.
     
  4. Aug 8, 2017 #3
    Thanks for your answer, Scott!
    How about small peace of "absorb sound material" (used in record studios) and ultrasound between 20 kHz and 40 kHz.
    Do you think it will work ?
     
  5. Aug 8, 2017 #4

    Nidum

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    Not quite an answer to your question but you might find the subject of Ultrasonic Welding interesting .

    Just put the two keywords into your search engine .
     
  6. Aug 10, 2017 #5
    I have worked with anechoic chambers - and with multi-kilowatt speakers. The first thing I noticed is that even a sealed metal chamber lined with the black absorbing foam does not stop all of the sound. The other thing is that it doesn't take much energy to make something incredibly loud.

    So to avoid damaging you ears or other body parts, I would be very, very careful in how you experiment - even with the ultrasonic frequencies between 20KHz to 40KHz. Also, do your speakers and that sound absorbing material work well at ultrasonic frequencies?

    Next, find a way of driving a significant percentage of the energy out in the form of sound waves that are concentrated in a small area. For example, the loud hailers I was working with could pump out more than 1Kwatt each. But the area at the front of the cone was 5 or 6 square feet. So it would have taken quite a while to burn anything with that sound.
     
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