Cross-sectional mapping of residual stresses by measuring the surface contour after a cut

A powerful new method for residual stress measurement is presented. A parr is cut in two, and the contour, or profile, of the resulting new surface is measured to determine the displacements caused by release of the residual stresses. Analytically, for example using a finite element model, the oppos ite of the measured contour is applied to the surface as a displacement bou ndary condition. By Bueckner's superposition principle, this calculation gi ves the original residual stresses normal to the plane of the cut. This "co ntour method" is more powerful than other relaxation methods because it can determine an arbitrary cross-sectional area map of residual stress, yet mo re simple because the stresses can be determined directly from the data wit hout a tedious inversion technique. The new method is verified with a numer ical simulation, then experimentally validated on a steel beam with a known residual stress profile.