Digital Volume Correlation Applied to X‐ray Tomography Images from Spherical Indentation Tests on Lightweight Gypsum

Cylinders made of lightweight gypsum are extracted from industrial plasterboard and then indented in situ in an X‐ray tomograph. The results from the in situ experiment show that a compacted zone develops under the indenter, which is displaying a very sharp boundary with the undamaged material. Tomographic imaging during the mechanical load associated with digital volume correlation enables the displacement fields to be measured during the test. However, because of the inhomogeneous nature of the indentation test, a high spatial resolution for the displacement is called for, and because the range of displacement amplitudes is small, uncertainties on the measured displacement and strain fields are large. In this study, a new methodology is presented to address integrated digital volume correlation based on a library of fields computed from a commercial finite element software. It allows many fluctuations in the estimated displacement fields to be filtered out and the measurement to be much more robust and reliable. This opens new pathways for the identification of mechanical properties.