A Spatio-temporal Approach for iDIC-Residual Stress Measurement

Recently, the Integrated-Digital Image Correlation (iDIC) has been proposed as a simple and effective approach for residual stress measurement. iDIC is a variant of the classical Digital Image Correlation where the “standard” displacement functions are replaced by problem-specific ones. By this simple modification, stress components become the unknowns of the problem, thus allowing a single-pass analysis. However, implementation of the Integral Method for estimation of depth-dependent Residual Stress components is difficult. In particular, the Least Squares approach is not possible. This work suggests a two-pass approach: in the former the direct solution of the triangular linear system is solved. In the latter, the previous estimates are used as starting point for a global minimization involving all the acquired images.