Simultaneous Assessment of Mechanical Properties and Boundary Conditions Based on Digital Image Correlation

In this study, reference is made to a mixed numerical-experimental methodology proposed in Fedele et alii [1], based on full-field kinematic measurements at the micro-scale provided by 2D Digital Image Correlation. The aim was to estimate mechanical properties of joints or interfaces in industrial manufacts. An adhesively bonded assembly for aerospace engineering was characterized by the above methodology, optically monitoring a small subdomain over the sample surface during non-conventional mixed mode experiments. An extension of the original approach is proposed herein, since the estimation of cohesive parameters, and the identification of the "actual" displacements to be prescribed locally along the boundary, are tackled simultaneously in a coupled framework. Due to ill-posedness and high dimensionality of the extended inverse formulation, exceeding a few thousand unknowns, recourse is made to an alternating minimization strategy. Suitable regularizing provisions are implemented, concerning the a priori regularity of boundary displacements and an equilibrium (Neumann) condition along the debonded part of the joint.