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Contour Method:
Measuring the Surface Contour

 
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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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Residual Stress
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this page: measure surface
Measure Surface

**** You can also measure the surface using laser scanning. See this paper: download paper M. B. Prime, R. J. Sebring, J. M. Edwards, D. J. Hughes, P. J. Webster, "Laser Surface-Contouring and Spline Data-Smoothing for Residual Stress Measurement," Experimental Mechanics, 44(2), pp. 176-184, April 2004.(LA-UR-02-7241)

Probably the simplest and most widely available way to measure the contour of the newly cut surface is to use a Coordinate Measuring Machine or CMM

photo of CMM

A CMM positions a touch trigger probe using a precision 2-axis (x,y) control system.

CMM's come in sizes ranging from desktop size to big enough to measure cars.

Picture: Brown and Sharpe

Photo of probe tip

Then the touch trigger probe registers contact with the surface. The location of the probe tip is combined with the machine coordinates to give a 3-D position of the surface.

Common tips include ruby spheres of 1-10 mm in diameter.

  • CMM's can automatically scan a surface and measure thousands of data points quickly.
  • A few micron precision is readily achievable
  • CMM's are widely available in inspection labs and machine shops at Universities and private shop

 

 

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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: March 12, 2007

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