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553 views
08:39 Jun-06-2006

Jeff Medford

NDT Inspector
Nucor Steel,
USA,
Joined Apr 2005
6
Air Couple Testing

Has it implemented in manual application yet. Also can it possibly have a higher freq. used to ensure that the sensitivity is adaquate? Refering to 2.25 or 5 Mhz


 
00:01 Jun-08-2006

Dave Forsyth

R & D
TRI/Austin,
USA,
Joined Nov 2001
41
Re: Air Couple Testing ----------- Start Original Message -----------
: Has it implemented in manual application yet. Also can it possibly have a higher freq. used to ensure that the sensitivity is adaquate? Refering to 2.25 or 5 Mhz
------------ End Original Message ------------

No commercial manual air-coupled UT I know of.

Air itself is the limiting factor in frequencies, sound does not propagate well in air at 2MHz, and is virtually zero propagation at any higher frequencies.

The sensitivity is not usually a function of frequency for air-coupled UT, rather it is the large impedance change at boundaries with solids. So you can get only a small fraction of energy into a solid from an air-coupled UT transducer using conventional UT techniques.

There are some interesting things that can be done with air-coupled UT that are not possible with immersion or contact UT, such as surface profiling, resonance spectroscopy, etc. There are also some engineering structures that are of very low density and air-coupled UT hasan advantage here.

Dave.




 


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