FCP Report No. 167

Crack Closure in Weldments

by

C. Y. Hou
F. V. Lawrence
Departments of Civil and Material Science and Engineering

Abstract

The strip-yield model for notched components (SYMNC model) which is based on Newman’s model for crack closure was used to simulate the fatigue behavior of welded joints. A special finite element mesh was needed to estimate the loading-direction plastic stretches at the weld toe because of its asymmetrical shape. These notch-tip plastic stretches were combined with the crack-tip plastic stretches to estimate the effective stress-intensity factor ratio as a function of crack length. The predictions of the SYMNC model showed that the crack closure of a stress-relieved weldment is affected by the weld-toe plastic zone for the cases of stress ratio R = 0. The observed crack-closure behavior of an as-welded T-joint with residual stresses was also predicted using the SYMNC model.

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