Towards Evaluation by Digital Image Correlation Method of the Depth-Inhomogeneous Residual Stresses in an Isotropic Material

An approach is proposed to determine the depth-inhomogeneous residual stresses in an isotropic material using digital image correlation of the displacement fields that appear at each step of drilling a small probe hole. This approach differs from the well-known approach in that cumulative summation of discrete displacement fields is performed and correction (calibration) coefficients are determined by finite element modeling for depth-averaged stresses. Mathematical modeling is used to analyze the influence of the factors accompanying drilling, namely, noise in a measuring system and uninformative (contaminated with drilling products) zones, on the displacement fields, and the results obtained are used to propose an optimum procedure for calculating inhomogeneous residual stresses.