Residual Stress Effects in Fatigue of Welded Joints

Abstract

Experimental results from constant amplitude fatigue tests are analyzed to account for the possible effect of residual stresses induced by welding of the specimens. It is shown that large amplitude precycling of a welded specimen can significantly change the S‐N curve for the specimen. Primarily the precycling reduces the fatigue damage caused by subsequent small amplitude cycles. Using simple hypotheses for the initial stress state and the following stress‐strain behavior, it is shown that Gerber's formula for the effect of mean stress gives results agreeing with the experimental data. Finally it is shown that consideration of residual stresses changes the S‐N curve enough to cause significant modification of the variable amplitude fatigue life predicted by the Rayleigh approximation.