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Technical Discussions
Håkan Sahlén
Håkan Sahlén
01:18 Oct-16-1998
Information about couplant-free ultrasonic transducers

Hi,
I'm currently working on my Master Thesis in Science and I wonder if anyone have any idea where I could find information about couplant-free transducers, e.g. articles, websites, or contacts. I've tried to search for it in various databases, but with very little success.
The transducers are supposed to work for transversal waves in the frequeny range around 2-5MHz and for flaw detection in steel constructions.

I would be greatful for any help.
Best regards, Håkan


    
 
 Reply 
 
Paul Meyer
R & D,
GE Inspection Technologies, USA, Joined Nov 1998, 47

Paul Meyer

R & D,
GE Inspection Technologies,
USA,
Joined Nov 1998
47
03:27 Oct-16-1998
Re: Information about couplant-free ultrasonic transducers
Hi Hakan,
These might be ElectroMagnetic Acoustic Transducers (EMATs). They induce a surface motion in the part using electromagnetic forces as the name implies and therefore need no couplant. Depending on the design of the field coils compressional or transverse waves can be generated.
Paul

: Hi,
: I'm currently working on my Master Thesis in Science and I wonder if anyone have any idea where I could find information about couplant-free transducers, e.g. articles, websites, or contacts. I've tried to search for it in various databases, but with very little success.
: The transducers are supposed to work for transversal waves in the frequeny range around 2-5MHz and for flaw detection in steel constructions.

: I would be greatful for any help.
: Best regards, Håkan




    
 
 Reply 
 
Richard D. Roberts
Engineering, Executive Managment
Quest Integrity Group, USA, Joined Nov 1998, 78

Richard D. Roberts

Engineering, Executive Managment
Quest Integrity Group,
USA,
Joined Nov 1998
78
05:54 Oct-16-1998
Re: Information about couplant-free ultrasonic transducers
: Hi,
: I'm currently working on my Master Thesis in Science and I wonder if anyone have any idea where I could find information about couplant-free transducers, e.g. articles, websites, or contacts. I've tried to search for it in various databases, but with very little success.
: The transducers are supposed to work for transversal waves in the frequeny range around 2-5MHz and for flaw detection in steel constructions.

: I would be greatful for any help.
: Best regards, Håkan

--------------------------
Hakan,

I know of a company located in Kennewick, Washington, USA that makes couplant free ultrasonic wheel probes. The wheel probes have a soft membrane material on the outer radius, which acts as the couplant. The elements cab be straight beam or angled to focus at a specified depth. These probes have been mounted on mechanical scanners or just used manually. I have only had experience with the Dual Crystal wheel probes and was quite impressed with the resolution they were able to achieve. This company is called SIGMA TRANSDUCERS, INC. and they can be reached at 1-509-783-9497.

Regards,
Richard D. Roberts
QUEST Integrated, Inc.




    
 
 Reply 
 
Michel Brassard
Michel Brassard
06:26 Oct-16-1998
Re: Information about couplant-free ultrasonic transducers
Håkan,

Our company can help you understanding EMATs. We manufacture EMATs for a variety of use and have engineers and scientists that would be pleased to guide in your research.

Michel Brassard , Tektrend Interantional

Hi,
: I'm currently working on my Master Thesis in Science and I wonder if anyone have any idea where I could find information about couplant-free transducers, e.g. articles, websites, or contacts. I've tried to search for it in various databases, but with very little success.
: The transducers are supposed to work for transversal waves in the frequeny range around 2-5MHz and for flaw detection in steel constructions.

: I would be greatful for any help.
: Best regards, Håkan




    
 
 Reply 
 
Håkan Sahlén
Håkan Sahlén
04:34 Oct-29-1998
Again: Ultrasonic transducer with alternative couplant material
Hi,
Thank you Michel, Richard, and Paul, for trying to help me out with my earlier question. I'm afraid I kind of mislead you with the way I put the words together.
Anyway, what I am looking for is some sort of material as an alternative to the one used as couplant (e.g. honey) for shear waves. And I rather not, for different reasons attach the transducer to the material with epoxi or similar.
If anyone could give some hints, who to talk to, or articles, or similar, it would mean a lot to me.

Once again, I'm grateful for any help,
Best regards,
Håkan Sahlén


    
 
 Reply 
 
Paul Meyer
R & D,
GE Inspection Technologies, USA, Joined Nov 1998, 47

Paul Meyer

R & D,
GE Inspection Technologies,
USA,
Joined Nov 1998
47
05:50 Oct-29-1998
Re: Again: Ultrasonic transducer with alternative couplant material
Hi Haken,
You can try castable materials that cure to a rubber-like hardness. Two-part RTV's (Room Temperature Vulcanizing materials) might work well at transmitting shear waves into a part because they have a "sticky" surface but they tend to be lossy. Place a thin sheet of the cured material between the transducer and the testpiece and perform a test. Try different materials, when you find one with acceptable performance, cast a thin layer directly onto the face of your probe and then ypu can performa several test iterations until the coupling layer is damaged or too caotaminated to use.
Paul
: Hi,
: Thank you Michel, Richard, and Paul, for trying to help me out with my earlier question. I'm afraid I kind of mislead you with the way I put the words together.
: Anyway, what I am looking for is some sort of material as an alternative to the one used as couplant (e.g. honey) for shear waves. And I rather not, for different reasons attach the transducer to the material with epoxi or similar.
: If anyone could give some hints, who to talk to, or articles, or similar, it would mean a lot to me.

: Once again, I'm grateful for any help,
: Best regards,
: Håkan Sahlén




    
 
 Reply 
 
Hermann Wustenberg
Hermann Wustenberg
08:15 Oct-29-1998
Re: Again: Ultrasonic transducer with alternative couplant material
Concerning dry coupling of shear waves

A very simple mean to achieve a reliable coupling on steel or other metallic material is the use of thin Aluminium foils (e.g. for packaging chocolate or other sweets) between the probe and the surface of your object. With a light manually applied pressure and a simultaneously executed rotation of the piezoceramic Shear-Wave Probe you will arrive at a reasonable coupling of the ultrasonic shear waves. This is probably due to the momentaneous contact of surface roughness peaks thereby producing a transfer of tangential forces.

Try it!

Hermann Wüstenberg
: Hi Haken,
: You can try castable materials that cure to a rubber-like hardness. Two-part RTV's (Room Temperature Vulcanizing materials) might work well at transmitting shear waves into a part because they have a "sticky" surface but they tend to be lossy. Place a thin sheet of the cured material between the transducer and the testpiece and perform a test. Try different materials, when you find one with acceptable performance, cast a thin layer directly onto the face of your probe and then ypu can performa several test iterations until the coupling layer is damaged or too caotaminated to use.
: Paul
: : Hi,
: : Thank you Michel, Richard, and Paul, for trying to help me out with my earlier question. I'm afraid I kind of mislead you with the way I put the words together.
: : Anyway, what I am looking for is some sort of material as an alternative to the one used as couplant (e.g. honey) for shear waves. And I rather not, for different reasons attach the transducer to the material with epoxi or similar.
: : If anyone could give some hints, who to talk to, or articles, or similar, it would mean a lot to me.

: : Once again, I'm grateful for any help,
: : Best regards,
: : Håkan Sahlén




    
 
 Reply 
 
Rolf Diederichs
Director,
NDT.net, Germany, Joined Nov 1998, 605

Rolf Diederichs

Director,
NDT.net,
Germany,
Joined Nov 1998
605
01:13 Oct-29-1998
Re: Again: Ultrasonic transducer with alternative couplant material

: If anyone could give some hints, who to talk to, or articles, or similar, it would mean a lot to me.

: Once again, I'm grateful for any help,
: Best regards,
: Håkan Sahlén




    
 
 Reply 
 
Satish
Satish
03:29 Apr-15-1999
Re: Information about couplant-free ultrasonic transducers
: Hi,
: I'm currently working on my Master Thesis in Science and I wonder if anyone have any idea where I could find information about couplant-free transducers, e.g. articles, websites, or contacts. I've tried to search for it in various databases, but with very little success.
: The transducers are supposed to work for transversal waves in the frequeny range around 2-5MHz and for flaw detection in steel constructions.

: I would be greatful for any help.
: Best regards, Håkan




    
 
 Reply 
 
Mario Alberto Quintero Carvajal
Mario Alberto Quintero Carvajal
07:12 Jul-13-2001
Re: Information about couplant-free ultrasonic transducers
hello,

I ned work with ultrasonic but i not know,
please, send me information.

tansk

one question, yours sale ultrasonic?


    
 
 Reply 
 

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