Displacement Discontinuity or Complex Shape of Sample: Assessment of Accuracy and Adaptation of Local DIC Approach

Abstract In this paper, we study the impact of a complex shape of sample and the appearance of a displacement discontinuity on performances of measurement by local Digital Image Correlation (DIC). Both cases are modelled from synthetic images into two parts: one with a speckle field and another part without speckle or two parts with similar speckle fields but with different kinematics. The accuracy of displacement measurements assessed for DIC subsets crossing the boundary between the two parts is lower than the one obtained without discontinuity and justifies adapting DIC method. A new local DIC process is presented in detail. It is an alternative way able to take into account any shape of sample and several curved lines of discontinuity in the same subset. Two experimental examples are presented: displacement and strain fields obtained by DIC and adapted DIC are compared. We can conclude that it is possible to lead a mechanical analysis until the limits of the sample and even during the appearance and the propagation of a crack.