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07:31 Jun-29-2009

Vikram

NDT Inspector, - Phased Array Specialist
Mistras Group Inc.,
USA,
Joined Jun 2009
9
Phased Array Steering Limits - Calculations

I wonder how the calculation for the beam steering in a phased array transducer goes:

For circular transducers the formula is 0.514 X (Wavelength)/ (Dia. of the transducer). How does that translate to finding the steering limits of a 5MHz, 16 element probe with a pitch of 0.6mm and a smallest possible element size of 0.2mm. The calculations do not make much sense when done but I know there was certain discussions before here about comparing rectangular and circular transducer.

 
16:44 Jun-29-2009

Roger Duwe

NDT Inspector, API-510, 570, 653
MISTRAS,
USA,
Joined Jan 2009
148
Re: Phased Array Steering Limits - Calculations In Reply to Vikram at 07:31 Jun-29-2009 (Opening).

Just a thought -- why not 'ask the transducer'. Try setting up a DAC curve using a 40 to 70 degree sectoral scan ['ducer on a wedge of approx 50 deg]. If it calibrates OK, try 35 to 75 or similar. If it cal's poorly, reduce the span of the scan angle.

My experience with 5L16's [5 MHz Linear 16-element] is that 50 to 70 degrees calibrates fine, 45 to 70 is problematic. Calculations make quite a few assumptions that may or may not hold true in the 'Real World'. Eventually, you will have to calibrate your system with that 'ducer. Why not now?

 
20:48 Jun-29-2009

Vikram

NDT Inspector, - Phased Array Specialist
Mistras Group Inc.,
USA,
Joined Jun 2009
9
Re: Phased Array Steering Limits - Calculations In Reply to Roger Duwe at 16:44 Jun-29-2009 .

Funny that you mention it, I just did the calculations for a SDH of 0.0625" to check the beam steering capability for an L-wave. I am going to extend the same for shear wave and get the results.

 


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