Evaluation of the Size of the Inelastic Deformation Zone at a Crack Tip Based on the Analysis of Displacement Fields

The damaged zone (the inelastic deformation zone) near a crack tip is the region where the stress–strain state (SSS) cannot be described by fundamental functions in the solution of the elastic problem of a crack (the Williams solution). For the description of SSS outside the damaged zone, the Williams expansion is used, which requires a number of regular terms to be considered. It is proposed to use digital optical techniques for measuring the SSS parameters in the crack zone to provide a large amount of experimental information in the form of displacement fields on the surface of the studied object directly in digital form.