Contour Method Advanced Applications: Hoop Stresses in Cylinders and Discontinuities
The traditional contour method measures a cross-sectional map of residual stress by cutting a body carefully in two and measuring the surface contour. This talk will present two new advances, both motivated by the measurement of a single challenging part. The first advance is a two-step process for measuring hoop stresses in cylinders. In the first step, a cut is made to split the cylinder (from an “o” cross-section to a “c”). That cut releases a bending moment which would otherwise causes errors in the contour measurement. The amount the cylinder springs open or closed is measured and used to determine the bending moment stresses. In the second step, the traditional contour method is applied: a cut is made to measure the remaining hoop stresses on a cross section normal to the hoop direction. The total residual stresses are given by superimposing the bending stresses and the remaining stresses. In this paper, the two-step process is applied to measuring the stresses in a circumferential welded cylinder of depleted uranium and is compared to neutron diffraction results. The welded cylinder also contains a further measurement complication. The weld was only partial penetration, leaving part of the joint unwelded. The measured surface contour therefore had a discontinuity across the joint. Proper handling of the surface discontinuity is presented.
KeywordsResidual Stress Neutron Diffraction Hoop Stress Residual Stress Measurement Contour Method
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