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- since 1996 -

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Technical Discussions
Steve Flanders
Steve Flanders
07:41 Oct-20-2003
European Craft Proposal - "All Optical Non-Destructive testing"

Light-Tap
All Optical Non-Destructive Testing
The main project objective is to develop a remotely operated, on-stream, non-contact, non-destructive testing (NDT) system that can monitor these vital components in-situ whilst at high temperature. The advantage of the proposed innovation compared with existing technology is its ability to assess the structural integrity of a high temperature metallic object whilst the object continues to operate. This is clearly a major improvement on the current technology, and will result in direct economic, logistic and efficiency savings for the industrial processes in question. In particular it will remove the great inconvenience and financial penalty associated with shutting down an entire process line in order to make structural integrity measurements on a single object.

This proposal will investigate an all-optical non-contact NDT system, which can be used to test objects at any temperature. The test will involve two laser pulses: the first a "tap" to vibrate the object, and the second to listen to the subsequent "noise". The "tap" is a highly focused, very high energy, very brief pulse, which heats up a tiny region of the object under test almost instantaneously. The dramatic expansion of this region causes a very small wave to propagate through the object, which is reflected from the internal structure of the object back to the source. The second laser pulse is a much lower energy, collimated pulse of laser light, which is reflected back from the surface of the object. By interfering this reflected light with a reference beam (which could be from the same laser), information on the surface, which is distorted by the returning waves in the object from the "tap" pulse, may be obtained. This information in turn can be used to deduce the internal structure of the object under test. By scanning the target location of the beams in a raster fashion, a "map" of the object may be constructed, and cracks and imperfections may be identified.



 
 Reply 
 
Keith
Keith
08:55 Oct-20-2003
Re: European Craft Proposal - "All Optical Non-Destructive testing"
Will the rapid heating and subsequent rapid cooling of the small surface area lead to a spot on the surface having tensile rather than compressive stress, which will be a starting point for cracks to develop later ?
----------- Start Original Message -----------
: Light-Tap
: All Optical Non-Destructive Testing
: The main project objective is to develop a remotely operated, on-stream, non-contact, non-destructive testing (NDT) system that can monitor these vital components in-situ whilst at high temperature. The advantage of the proposed innovation compared with existing technology is its ability to assess the structural integrity of a high temperature metallic object whilst the object continues to operate. This is clearly a major improvement on the current technology, and will result in direct economic, logistic and efficiency savings for the industrial processes in question. In particular it will remove the great inconvenience and financial penalty associated with shutting down an entire process line in order to make structural integrity measurements on a single object.
: This proposal will investigate an all-optical non-contact NDT system, which can be used to test objects at any temperature. The test will involve two laser pulses: the first a "tap" to vibrate the object, and the second to listen to the subsequent "noise". The "tap" is a highly focused, very high energy, very brief pulse, which heats up a tiny region of the object under test almost instantaneously. The dramatic expansion of this region causes a very small wave to propagate through the object, which is reflected from the internal structure of the object back to the source. The second laser pulse is a much lower energy, collimated pulse of laser light, which is reflected back from the surface of the object. By interfering this reflected light with a reference beam (which could be from the same laser), information on the surface, which is distorted by the returning waves in the object from the "tap" pulse, may be obtained. This information in turn can be used to deduce the internal structure of the object under test. By scanning the target location of the beams in a raster fashion, a "map" of the object may be constructed, and cracks and imperfections may be identified.
------------ End Original Message ------------




 
 Reply 
 
Roland
Roland
02:40 Oct-21-2003
Re: European Craft Proposal - "All Optical Non-Destructive testing"
Hello Steve.

I think that this Idea will be very interesting, but I would like to know what kind of cracks you can measures.
I had been work in NDT since 4 years a go but in wood industry application, in orden to grade the products in the industry, or in situ in the structure architecture.
In principle that maybe interesting if your idea could be apply in the non isotropic materials like wood.
If you cosider this point of vew interesting don´t hesitate to contact me
Sincerely yours
Roland.


 
 Reply 
 
John O'Brien
Consultant, -
Chevron ETC , USA, Joined Jan 2000, 280

John O'Brien

Consultant, -
Chevron ETC ,
USA,
Joined Jan 2000
280
08:07 Oct-22-2003
Re: European Craft Proposal - "All Optical Non-Destructive testing"
Roland

your application sounds similar to soemtihing I saw in the USA recently. The system was being used to grade the surface finish of machined wooden doors for kitchens etc.

The system I saw used a stylus and AE approach to detection acceptable/unacceptable wood surface finish.



 
 Reply 
 
Wolfgang Bisle
R & D, senior Engineer and nomiated Expert
retired from Airbus Deutschland GmbH, Germany, Joined Jul 2000, 37

Wolfgang Bisle

R & D, senior Engineer and nomiated Expert
retired from Airbus Deutschland GmbH,
Germany,
Joined Jul 2000
37
09:22 Nov-11-2003
Re: European Craft Proposal - "All Optical Non-Destructive testing"
Sounds not very new.

Is something like laserultrasonics.
AIRBUS is working on that already since years.
INCA is the current project in the 5th framework.
System in use are at Lockheed Martin for JSF production inspection, at Timken and Mannesmann for Pipe inspection and so on. From UK it is reported that even a canary uses this technique to measure the Beer level in their cans.
Just this application for high temperature was already patented by Krautkramer in the early 80ies, if my memory doesn't cheat me.

So what is the innovation?



 
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