A Global Formulation to Stereo Digital Image Correlation with Mechanical Regularisation
Résumé
The aim of this study is to measure, with stereo digital image correlation, the displacements and rotations at the boundary of a plate subjected to complex loadings. With classical DIC techniques, the measured field is the displacement of the upper skin only. The rotations are usually estimated a posteriori by numerical differentiation and smoothing. Unfortunately additional uncertainties may arise with these steps. Conversely, the use of a finite element model is proposed here to regularise a stereo FE-DIC measurement. For that a formulation using the 3D displacement as primary unknown is introduced. It requires projection operators based on a pinhole camera model. It is shown that it is possible to take into account distortions directly. Associated to this formulation a more accurate quadrature technique is used avoiding a systematic bias.