Image Correlation for the accurate measurement of residual stress – ICAReS

The control of the residual stress distributions is a key industrial challenge across the scales. Experimental procedures have recently emerged to emphasize the localized effects of these stresses, to observe them with digital image correlation (DIC) and finally to characterize them. In such approaches, the accuracy of residual stress measurement directly relies on that of DIC. The ICAReS project circumvents the usual DIC metrological limitations and will by consequence dramatically improve residual stress measurement. For this purpose, a new version of DIC, named Virtual DIC, is introduced in this project. Its backbone is to rely on closed-form expressions of the image texture called virtual pattern. The real images will be the discretized versions of the virtual pattern because the latter will be deposited on the surface under study. New DIC issues are tackled with the constant goal of improving the metrological performance of the measuring method. In particular, the Virtual DIC will be optimized to determine (i) the residual stress distribution in an industrial representative micro-sample and (ii) the effect at the macro-size of their release due to machining.