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- since 1996 -
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Technical Discussions
Alex
,
Israel, Joined Sep 2017, 8

Alex

,
Israel,
Joined Sep 2017
8
09:11 Sep-27-2017
Looking for broad bandwidth ultrasonic transducer

Need your advice experts. I'm looking for broad bandwidth ultrasonic transducer, say 500 kHz to 10 MHz range, maximum sensor diameter size of 1in.
I have to test a couple of composite materials and with the broad bw transducer I want to detect the optimal frequency to work with.

Will appreciate any help and advice!

 
 Reply 
 
Alex
,
Israel, Joined Sep 2017, 8

Alex

,
Israel,
Joined Sep 2017
8
09:46 Sep-27-2017
Re: Looking for broad bandwidth ultrasonic transducer
In Reply to Alex at 09:11 Sep-27-2017 (Opening).

To be specific the material is glass-phenolic, 15 mm thick, sound velocity 2417 m/s

 
 Reply 
 
Wieslaw Bicz
Engineering,
PBP Optel sp. z o.o., Poland, Joined Feb 2009, 271

Wieslaw Bicz

Engineering,
PBP Optel sp. z o.o.,
Poland,
Joined Feb 2009
271
12:12 Sep-28-2017
Re: Looking for broad bandwidth ultrasonic transducer
In Reply to Alex at 09:11 Sep-27-2017 (Opening).

It is possible to make such transducer, but if this should be used as sender and receiver with some power it will be difficult. We have made such transducer, composed from different elements, working with different frequencies, but the cost for such device would be very high.

In your case it makes much more sense to check simply the attenuation in your material using some standard transducer with different frequencies and based on this chose the most suitable one.

I would suggest to start with 2 MHz and check, if this will deliver good signal.

 
 Reply 
 
Alex
Alex
14:51 Sep-28-2017
Re: Looking for broad bandwidth ultrasonic transducer
In Reply to Wieslaw Bicz at 12:12 Sep-28-2017 .

Thank you for your respond! Is it possible using 3-4 transducers with different frequency and material with 1 certain thickness to measure the frequency and distance dependent attenuation? How based on the measurement I can find the optimal frequency that provides both backscatter echo and surface echo?

 
 Reply 
 
Alex
Alex
15:01 Sep-28-2017
Re: Looking for broad bandwidth ultrasonic transducer
In Reply to Alex at 14:51 Sep-28-2017 .

To be more specific, I want to find the maximum frequency (for higher axial resolution) allowing to recognize the surface and back-scatter echo.

 
 Reply 
 
James Scalf
NDT Inspector,
Global Integrity, Canada, Joined Oct 2012, 274

James Scalf

NDT Inspector,
Global Integrity,
Canada,
Joined Oct 2012
274
18:54 Sep-29-2017
Re: Looking for broad bandwidth ultrasonic transducer
In Reply to Alex at 09:11 Sep-27-2017 (Opening).

Alex,

GE Inspection Technologies used to produce what they called the "ZIP" (Zero Interface Probes) Probe it was specific manufactured for the examination of composite and ceramic glass materials and came in a variety of frequencies from 750kHz to 2.0 MHz. Maybe reach out to a local GE Representative in your area and see or look at their website. Here is a link for the GE Probe catalogue from NDT Products here in Canada http://www.ndtproducts.ca/products/files/UT%20Probe%20Cat.pdf.

Hope this helped. Cheers...

James

1
 
 Reply 
 
J.B.
J.B.
20:39 Oct-04-2017
Re: Looking for broad bandwidth ultrasonic transducer
In Reply to James Scalf at 18:54 Sep-29-2017 .

The materiel you like to work with is similar to CFRP, so the selection of transducer depends also on the thickness of the structure you have to inspect.
Thin material can be easily tested with up to 10MHz, we liked the alpha aerotech series from GE or camparable transducers from Panametrics/Olympus with rising thickness you may go down to 5MHz or 3.5MHz. 10..20mm thickness. Really thick strutures (>30mm) need low frequencies, we had very good expereince with MK2S (Krautkramer) - it is a good compromize and is rather broad band.

You may finetune the selection of transducers if you gate the echo signal and feed it into a spectrum analyzer or use a FFT if included in your inspection device software ( or digitize the full A-scan and use e.g. "Labview"- software to analyze the signal. Be aware: you need to cut out the flaw echo or the backwall echo and by t a propper window (e.g. hamming window) If the windowing is done wrong, you get a lot of intermodulation which lead you to completely wrong frequency selection. you should know the physics and mathematics behind FFT, otherwise you will do stupid things. Ipreferred in the past analogue UT equipment like the USIP12 and coupled it with a mixing Spectrum Analyzer e.g. from Rhode&Schwarz to do such freuquency analytics - those old fashioned ananlogue instruments work much easier that the digital ones today, and you see much quicker, where may make mistakes. Sadly analogue electronics have vanished from the scene... people now trust in didgital but do not now really the obstacles of digitazation (e.g. quantification errors etc.)

 
 Reply 
 
Simon Amallraja
Consultant, Advanced NDT Methods
Anu Consultants, India, Joined Aug 2013, 40

Simon Amallraja

Consultant, Advanced NDT Methods
Anu Consultants,
India,
Joined Aug 2013
40
13:22 Oct-10-2017
Re: Looking for broad bandwidth ultrasonic transducer
In Reply to Alex at 09:11 Sep-27-2017 (Opening).

You can try it from Ultran Group, USA. You can try Air Coupled Probes or Contact Probes with delay lines (GRD range) to support this reqt. I suggest to use any tone burst Pulser Receiver for better results.

 
 Reply 
 

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