Strain Distributions around Cracks in Ductile Sheets during Loading and Unloading

Abstract
Strain distributions around fatigue cracks in different sheet metals have been obtained by using a photoelastic surface coating with a reflection polariscope. It is shown that an estimate of the distribution of the maximum shear strain, y, near the crack tip, during both loading and unloading of the sheet, requires a knowledge of only the stress-strain curve of the material and the theoretical elastic plane-stress solution.