Shear-band capturing using a multiscale extended digital image correlation technique

Finite elements have been used recently to solve the optical flow conservation principle invoked to determine displacement fields by digital image correlation. Inspired by these recent advances, and by the computational effort that has been accomplished during the past 10 years for the simulation of discontinuities by the extended finite element method (XFEM), an extended correlation technique is introduced for capturing shear-band like discontinuities from images of real mechanical tests. Because of the specific information at hand (i.e., gray level images), this extended finite element approach is included in a non-linear multi-grid solver. The performances of the proposed approach are discussed on two examples, namely the analysis of a bolted assembly and the formation of Piobert–Lüders bands.