Material analysis via sound absorption

[alpha_wolf]

It has been mentioned in one of the other forums that different materials absorb different sound frequencies, and a suggestion was raised to use that for material analysis. Is this sort of testing actually being done? If so, what information can be found about the material this way?

[ZapperZ]

It has been mentioned in one of the other forums that different materials absorb different sound frequencies, and a suggestion was raised to use that for material analysis. Is this sort of testing actually being done? If so, what information can be found about the material this way?

Er.... you have heard of the widely-used ultrasound scan on a fetus during pregnancy, haven't you? It's the same principle done on materials.

Zz.

[alpha_wolf]

Yes, I know about ultrasound.. Wasn't sure if it's being used for material diagnostics though. Was that usltrasound that is being used for micro-fracture detection or was it something else? What other properties are being checked by ultrasound? Density distribution maybe? And also, what other sound based tests are there?

[Gokul43201]

The first thing that comes to mind is the use of ultrasonic probes for non-destructive Testing. Sound waves reflect of cracks, dislocation planes, cavities, etc. Google gives you several useful hits with "ultrasonic NDT".

The next thing that comes to mind is scattering off acoustic phonons. Neutron or X-ray scattering can be used to generate dispersion curves for the acoustic phonons. From this you can extract information about crystal symmetry, ionic masses, etc.

[Bilal]

In fact we use in our research group sound waves to check some material properties (e.g E modulus). There are link also with cracks, which is part of my current work.

[ZapperZ]

Not sure if anyone is still interested in this string, but just in case, there's a very good article related to acoustic microscopy:

http://www.tipmagazine.com/tip/INPHFA/vol-10/iss-3/p14.html

Zz.