On the Implementation of the Integral Method for Residual Stress Measurement by Integrated Digital Image Correlation

The Integrated Digital Image Correlation method (iDIC) is a simple and effective approach for residual stress measurement. iDIC differs from Digital Image Correlation because it replaces the "generic" displacement functions used to describe the displacement field around the measurement point with problem-specific ones. By this simple modification, stress components become the unknowns of the problem, thus allowing a single-pass analysis. Advantages are significant in terms of accuracy, robustness and ease of implementation. However, the implementation of the Integral Method for estimation of depth-dependent residual stress components is difficult. This work suggests two alternative approaches to solve this problem; in the former, the direct solution of the triangular linear system is employed to incrementally identify the stress distribution. In the latter, a global spatio-temporal minimization involving all the acquired images is suggested.