Feasibility study of 3D Digital Volume Correlation of synchrotron radiation laminography data for displacement field measurement during ductile crack initiation

Abstract : Three-dimensional (3D) digital volume correlation has recently been used to assess displacement fields in 3D via correlation of in-situ 3D x-ray tomography images. The intrinsic contrast due to microstructural heterogeneities is used in these cases as ‘natural 3D speckles’. In-situ tomography experiments are typically limited to specimens of diameter of ~1 mm when resolutions of ~1 μm are required. With synchrotron radiation laminography this limitation can be overcome as specimens with sizes of several centimetres in lateral dimensions and ~1 mm in thickness can be used. In the present study the data of an initiating crack in a ductile Al-alloy sheet with initial porosity and intermetallic particles as natural contrast has been acquired by synchrotron radiation laminography for different loading steps. The performance of the technique using laminography data is assessed via correlation of data from two scans of a non-deformed material at different locations within the scanned volume. The correlation of deformed material achieves similar residuals as that of non-deformed material, thereby suggesting successful correlation. The measured displacement fields found are consistent with the remote loading conditions.