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Residual Stress
Conferences |
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 Pagliaro, P. at al., 2011, "Measuring Inaccessible Residual Stresses Using Multiple Methods and Superposition," Experimental Mechanics, 51 (7):1123-1134.
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Standard contour method:
The contour method is usually used to measure only σx on the cut plane (x = 0), as shown on the left side of this figure.
Superposition method for multiple stress components:
But you can measures other stress components, like σz, on the cut surface after the cut. That measurement is σzB. Superposition will let you calculate the original stress:
Where you already have σzC from the FEM calculation of σx |
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Validation specimen:
- 60 mm diameter, 10 thick disk of Aluminum 2024-T351
- Indented in central 10 mm to induce residual stress
- Measured with neutron diffraction before cutting
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Experiment:
- Disk cut in half using wire EDM
- With usual contour method, this measures hoop stress
- Surface contours measured using laser scanner
- EDM-affected layer on cut surfaces by electropolishing
- One one cut surface (section plane in picture above), radial stresses measured using hole drilling
- On other cut surface, radial stresses measured using x-ray diffraction (photo left)
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Reconstruct radial stresses by superposition:
Once on each half of part:
 
And the final results agree with independent neutron measurements!
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