Architecture-Driven Digital Volume Correlation: Application to the Analysis of In-Situ Crushing of a Polyurethane Foam

Background Digital Volume correlation (DVC) consists in identifying the displacement fields that allow for the best possible registration of volume images of a sample captured at various loading stages. With cellular materials, the use of DVC faces an intrinsic limit: in the absence of an exploitable texture on (or in) the struts or cell walls, the available speckle pattern will unavoidably be formed by the material architecture itself. This leads to the inability of classical DVC techniques to measure kinematics below the cellular scale, i.e. at the sub-cellular or micro scales. Objectives Here, we extend a newly developed architecture-driven DIC technique [1] for the measurement of 3D displacement fields in real cellular materials at the scale of the architecture. Methods The proposed solution consists in assisting DVC by a weak elastic regularization using, as support, an automatic finite-element image-based mechanical model. Results Complex (locally buckling) kinematics of a polyurethane foam under compression are accurately measured during an in-situ test. The method is essential to evidence the class of dominance (stretching versus bending) of the foam. Conclusion The proposed method allows to confirm that the foam used is bending-dominated, which is not possible with a classical mesoscopic DVC approach. This method is a good candidate for the analysis of complex local deformation mechanisms at the architecture scale.