Measuring Inaccessible Residual Stresses Using MultipleudMethods and Superposition

摘要

The traditional contour method maps a singleudcomponent of residual stress by cutting a body carefully inudtwo and measuring the contour of the cut surface. The cut alsoudexposes previously inaccessible regions of the body toudresidual stress measurement using a variety of other techniques,udbut the stresses have been changed by the relaxationudafter cutting. In this paper, it is shown that superposition ofudstresses measured post-cutting with results from the contourudmethod analysis can determine the original (pre-cut) residualudstresses. The general superposition theory using Bueckner’sudprinciple is developed and limitations are discussed. Theudprocedure is experimentally demonstrated by determining theudtriaxial residual stress state on a cross section plane. The 2024-udT351 aluminum alloy test specimen was a disk plasticallyudindented to produce multiaxial residual stresses. After cuttingudthe disk in half, the stresses on the cut surface of one half wereuddetermined with X-ray diffraction and with hole drilling onudthe other half. To determine the original residual stresses, theudmeasured surface stresses were superimposed with the changeudstress calculated by the contour method. Within uncertainty,udthe results agreed with neutron diffraction measurementsudtaken on an uncut disk.