Applications: Bent Beam

 M. B. Prime, "Cross-Sectional Mapping of Residual Stresses by Measuring the Surface Contour After a Cut," Journal of Engineering Materials and Technology, 123, pp. 162-168, 2001. (LA-UR-00-205)

For more on this kind of known stress specimen, and x-ray and neutron results: M. B. Prime, P. Rangaswamy, M. R. Daymond, and T. G. Abeln, "Several Methods Applied to Measuring Residual Stress in a Known Specimen," Proc. SEM Spring Conf. on Experimental & Applied Mechanics, Houston, Texas, June 1-3, 1998, pp. 497-499. (LA-UR-98-0904)

Stress Map Measured Over Beam Cross-Section:
Bend Test Prediction	Measurement Results	Plot Scale
		Results also plotted as through-thickness curve. Agreement with prediction is very good!
Details of this measurement and specimen:
Steel Beam Austenitic stainless steel 10 mm X 30 mm cross section Bend to put in known residual stress Bend in 4-point bending fixture. Measure strain on top and bottom of beam during loading and unloading. Calculate residual stress from strains and loads.
Cut Beam using wire EDM Beam carefully clamped during cutting. Use 100 µm (0.004") diameter wire. Cut using "skim cut settings" so that minimal stresses are put in during cutting.
Measure Surface Contour with CMM Use 4 mm diameter ruby tip Measure 10 x 30 mm surface with a 50 x 300 grid of points.
Calculate Stress using FEM Make 3-D model of beam after cut. Apply opposite of measured contour as displacement boundary conditions. Extract stresses normal to surface.

Managed by Triad National Security, LLC 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: June 26, 2009