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Technical Discussions
Frank Lehmann
Frank Lehmann
04:12 Jun-30-2007
ultrasonic low-frequency flaw detection

Hello,

I recently started working with an ultrasonic low-frequency flaw detector. When trying to understand the principles this method is based on, I encountered some problems. Despite extensive research on the internet I couldn't find any answers to my questions and I'd kindly ask you to help me out. As a general information, the project I'm working on is a concrete tunnel lining. The goal is to measure its thickness and find existing flaws.

* When measuring the thickness of the concrete tunnel lining, depending on the pulse length, I get different results. The longer the pulse, the thicker the lining. Why and how does the pulse length influence my data?

* How does the sounding frequency of the antenna array influence my measuring results? Or does it?

* I was not able to find out how the antenna produces shear waves. The pertinent sites on the internet just talk about EMATs and Laser, of which both don't apply here I think. Of course it's some kind of piezoelectric transducer, but those I thought merely produce longitudinal waves.

* What is the advantage of an antenna array compared to a single probe?

* And last but most important for me, what is the advantage of shear waves in concrete testing -or in general- over compressive waves?

Thank you very much,
Frank Lehmann



 
 Reply 
 
test
test
02:29 Oct-28-2007
Re: ultrasonic low-frequency flaw detection
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----------- Start Original Message -----------
: Hello,
: I recently started working with an ultrasonic low-frequency flaw detector. When trying to understand the principles this method is based on, I encountered some problems. Despite extensive research on the internet I couldn't find any answers to my questions and I'd kindly ask you to help me out. As a general information, the project I'm working on is a concrete tunnel lining. The goal is to measure its thickness and find existing flaws.
: * When measuring the thickness of the concrete tunnel lining, depending on the pulse length, I get different results. The longer the pulse, the thicker the lining. Why and how does the pulse length influence my data?
: * How does the sounding frequency of the antenna array influence my measuring results? Or does it?
: * I was not able to find out how the antenna produces shear waves. The pertinent sites on the internet just talk about EMATs and Laser, of which both don't apply here I think. Of course it's some kind of piezoelectric transducer, but those I thought merely produce longitudinal waves.
: * What is the advantage of an antenna array compared to a single probe?
: * And last but most important for me, what is the advantage of shear waves in concrete testing -or in general- over compressive waves?
: Thank you very much,
: Frank Lehmann
------------ End Original Message ------------




 
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