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Technical Discussions
C Truskolasky
Test Examiner Mil-2132, Level III
Lehigh Heavy Forge, USA, Joined Jan 2007, 10

C Truskolasky

Test Examiner Mil-2132, Level III
Lehigh Heavy Forge,
USA,
Joined Jan 2007
10
01:28 Feb-27-2007
Panametric 1/4 x 1 Transducer

Does anyone have the near field depth for the Panametric 2.25MHz .25" x 1" Accuscan A1004.1 transducer?


 
 Reply 
 
Tom Nelligan
Engineering,
retired, USA, Joined Nov 1998, 390

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
08:56 Feb-28-2007
Re: Panametric 1/4 x 1 Transducer
The beam profile of a rectangular transducer is complex because near field length and beam spread angle will effectively be different across the long and short dimensions, and the actual sound pressure profile represents a combination of those effects. You can find a full discussion of the relevant physics in chapter 4.5 of the textbook "Ultrasonic Testing of Materials" by Krautkramer & Krautkramer.


----------- Start Original Message -----------
: Does anyone have the near field depth for the Panametric 2.25MHz .25" x 1" Accuscan A1004.1 transducer?
------------ End Original Message ------------




 
 Reply 
 
CTruskolasky
Test Examiner Mil-2132, Level III
Lehigh Heavy Forge, USA, Joined Jan 2007, 10

CTruskolasky

Test Examiner Mil-2132, Level III
Lehigh Heavy Forge,
USA,
Joined Jan 2007
10
09:27 Mar-01-2007
Re: Panametric 1/4 x 1 Transducer
----------- Start Original Message -----------
: Does anyone have the near field depth for the Panametric 2.25MHz .25" x 1" Accuscan A1004.1 transducer?
------------ End Original Message ------------

I had already used the Krautkramer text and ended up with various/skeptical results. I settled on the formula given in Table 6-1 of the "Phased Array Technical Guidelines", published by R/D Tech. It uses a correction factor based on the ratio of the width/length of the crystal. The .25 ratio results in a correction factor of .99 found in the graph of figure 6-1 of the same text. The near field length calculates to 61mm, (2.4-in) which is approx. the same for a 25mm (1.0-in)circular crystal. I was hoping someone would have already experimentally measured this value.


 
 Reply 
 
John Brunk
Engineering, NDT Level III
Self employed, part-time, USA, Joined Oct 1999, 162

John Brunk

Engineering, NDT Level III
Self employed, part-time,
USA,
Joined Oct 1999
162
02:48 Mar-02-2007
Re: Panametric 1/4 x 1 Transducer
----------- Start Original Message -----------
: : Does anyone have the near field depth for the Panametric 2.25MHz .25" x 1" Accuscan A1004.1 transducer?
: I had already used the Krautkramer text and ended up with various/skeptical results. I settled on the formula given in Table 6-1 of the "Phased Array Technical Guidelines", published by R/D Tech. It uses a correction factor based on the ratio of the width/length of the crystal. The .25 ratio results in a correction factor of .99 found in the graph of figure 6-1 of the same text. The near field length calculates to 61mm, (2.4-in) which is approx. the same for a 25mm (1.0-in)circular crystal. I was hoping someone would have already experimentally measured this value.
------------ End Original Message ------------

Any calculation of near field length assumes that the transducer operates at a single frequency, and this is never the case. An actual experimental measurement would seem to be the right thing to do. However, the results would applystrictly only to that particular transducer and ultrasonic instrument. Any manufacturer's "transducer characterization" will apply only to the particular transducer and the equipment and target used. If you look at these cahracterizations for a group of transducers having the same part number, each will be a little different from all the others. Pulser type and settings will have some effect on the output spectrum, and the bandwidth characteristics of the receiver will also impact the observed near field. I wonder why you would believe you need an exact near field length. It seems to me that there is no such thing in real life.



 
 Reply 
 
C Truskolasky
Test Examiner Mil-2132, Level III
Lehigh Heavy Forge, USA, Joined Jan 2007, 10

C Truskolasky

Test Examiner Mil-2132, Level III
Lehigh Heavy Forge,
USA,
Joined Jan 2007
10
03:46 Mar-04-2007
Re: Panametric 1/4 x 1 Transducer
----------- Start Original Message -----------
: : : Does anyone have the near field depth for the Panametric 2.25MHz .25" x 1" Accuscan A1004.1 transducer?
: : I had already used the Krautkramer text and ended up with various/skeptical results. I settled on the formula given in Table 6-1 of the "Phased Array Technical Guidelines", published by R/D Tech. It uses a correction factor based on the ratio of the width/length of the crystal. The .25 ratio results in a correction factor of .99 found in the graph of figure 6-1 of the same text. The near field length calculates to 61mm, (2.4-in) which is approx. the same for a 25mm (1.0-in)circular crystal. I was hoping someone would have already experimentally measured this value.
: Any calculation of near field length assumes that the transducer operates at a single frequency, and this is never the case. An actual experimental measurement would seem to be the right thing to do. However, the results would apply strictly only to that particular transducer and ultrasonic instrument. Any manufacturer's "transducer characterization" will apply only to the particular transducer and the equipment and target used. If you look at these cahracterizations for a group of transducers having the same part number, each will be a little different from all the others. Pulser type and settings will have some effect on the output spectrum, and the bandwidth characteristics of the receiver will also impact the observed near field. I wonder why you would believe you need an exact near field length. It seems to me that there is no such thing in real life.
------------ End Original Message ------------

I'm not looking for an exact length for the near field but just a good approximation. I'm attempting to make an AVG/DGS chart for this transducer.


 
 Reply 
 

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