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Contour Method: Principle

  
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> Principle
   - make cut
   - measure surface
   - calculate stress
Validations
Applications
   - bent beam
   - weld plate
   - quenched steel
   - impacted plate
   - alum. forging
   - friction stir weld
   - Ti FSW
   - Railroad rails
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More info
 
Residual Stress
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(See 2nd and 3rd paper on publications page for two ways to measure multiple stress components:
1) With multiple cuts and 2) Using one cut, multiple techniques, and superposition)

 

The Contour Method is Based on an Elastic Superposition Principle:

initial, unknown residual stress
Start with your part. These are the residual stresses that you would like to measure

Experimentally cut the part in two. The part will deform from the release of the stresses

Then experimentally measure the contour, or shape, of the newly created surface

 deformed shape after cutting
Now analytically force the cut surface back flat. This gives the original residual stresses normal to the cut plane! cut surface returned to original state
It really is simple, but gives you a full 2-D map of the original residual stresses over the cross-section of the part!
stress map

Details:

 

  
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Operated by Los Alamos National Security, LLC for the U.S. Department of Energy's NNSA
contact: Mike Prime at prime@lanl.gov | Copyright & Disclaimer
U.S. patent 6,470,756 | Last Modified: October 27, 2011

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