Mechanics-guided data-enhanced kinematic models for time-resolved DVC

X-ray Computed Tomography (XCT) combined with Digital Volume Correlation (DVC) enables for internal displacement and strain measurements in deforming materials. The long acquisition time of tomographic scans restricts analyses to a few static loading steps and prevents from time-dependent or nonlinear mechanism quantification. Projection-based DVC (P-DVC) addresses this limitation by exploiting projections acquired during continuous loading, providing substantially higher temporal sampling. This study assesses a spacetime framework of projection-enhanced DVC for the in situ investigation of a 3D-printed lattice. Global DVC displacement fields are used to construct reduced spatial bases, namely, (i) a pure data-driven basis, (ii) a mechanics-only basis derived from an elastic compression solution, and (iii) a hybrid mechanics-data basis combining both. P-DVC then exploits the projections to identify the temporal amplitudes associated with these modes, thereby reconstructing the time-resolved kinematics with a resolution of 3.7 s, nearly two orders of magnitude faster than conventional 3D-to-3D DVC. Nonlinear mechanisms were detected ahead of their clear expression in tomographic reconstructions. The hybrid reduced-order approach provided interpretable kinematic fields while preserving the predictive accuracy of data-driven strategies. The projection-enhanced DVC framework thus enabled for temporally dense and spatially resolved in situ measurements, providing the type of rich datasets required for the identification and learning of complex constitutive models.