Effect of Plastic Deformation on the Strain Distribution around Cracks in Sheet Materials

Abstract

The strain distributions around fatigue cracks in nine different sheet materials have been obtained using a photoelastic surface-coating technique. It was found that the strains in the local plastic region around the tip of the crack were higher than predicted by elastic theory. For the materials tested, except mild steel, the elastic-plastic maximum shear-strain γ distribution around a crack in a wide sheet could be estimated during loading from the expression , where E is the modulus of elasticity, E_s the secant modulus corresponding to γ, and γ₀ the elastic solution for the maximum shear strain.