Proper Generalized Decomposition stereocorrelation to measure kinematic fields for high speed impact on laminated glass

Stereocorrelation (SC) is a powerful tool for measuring 3D surface deformations in mechanical tests. However, it may suffer from convergence issues for large displacements or speckle changes. A global space-time formulation is proposed herein using Proper Generalized Decomposition (PGD) as a regularization strategy. The entire image sequence is considered as a whole, and the kinematics is sought as the sum of modes, each of which is a function of space multiplied by a function of time (smoothed over high frequencies if needed). A discriminative benchmark case is chosen to validate this approach: an impact test on glass laminated with PVB layers. This case is difficult for many reasons, particularly because of severe contrast changes due to light reflections occurring at several places. It is shown that the new formulation outperforms classical approaches in robustness and measurement accuracy and provides results within a much shorter processing time.