Synchrotron Laminography: A Technique for In situObservation of Damage and its Evolution Inside Engineering Materials

Lukas Helfen,^1,2Mark N. Mavrogordato,³Thilo F. Morgeneyer,⁴T. Baumbach¹

¹ Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology, PO Box 3640, D-76021 Karlsruhe, Germany

² European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex, France

³ µVIS X-ray Imaging Centre, Faculty of Engineering and the Environment, Southampton University, Southampton, SO17 1BJ, United Kingdom

⁴ Mines ParisTech, Centre des Matériaux, CNRS UMR 7633, BP 87, F-91003 Evry Cedex, France

lukas.helfen@kit.edu

Keywords: non-destructive characterisation, tomographic 3D imaging, synchrotron radiation.

 Abstract: Computed laminography has been established at synchrotron imaging set-ups to complement computed tomography for three-dimensional (3D) imaging of laterally extended (i.e. plate-like) specimens [1]. Due to different contrast modes (such as absorption, different phase-contrast modes, fluorescence, diffraction) available and spatial resolutions (in a parallel-beam geometry) ranging from about 30 down to approx. 0.5 µm, there is a wide application potential for flat samples in material research. Selected examples demonstrate the interest of the method especially forin situ measurements of large planar specimens where sample extraction needs to be avoided and/or engineering-relevant boundary conditions have to be fulfilled. In particular, progress about  3D damage characterisation in carbon-fibre composite panels [2,3] and about the in situ study of strain-damage interactions under mechanical loading in aluminium alloy sheets [4] is reported.

References:

1. Helfen, T. Baumbach, P. Mikulík, D. Kiel, P. Pernot, P. Cloetens, J. Baruchel (2005)High-Resolution Three-Dimensional Imaging of Flat Objects by Synchrotron-Radiation Computed Laminography. Appl. Phys. Lett. 86:071915
2. J. Bull, S.M. Spearing, I. Sinclair, L. Helfen (2013) Three-dimensional assessment of low velocity impact damage in composite laminates using micro-focus X-ray computed tomography and synchrotron-radiation laminography, Composites Part A52:62–69
3. Borstnar, M.N. Mavrogordato, L. Helfen, I. Sinclair, S.M. Spearing (2015)Interlaminar fracture micro-mechanisms in toughened carbon fibre reinforced plastics investigated via synchrotron radiation computed tomography and laminography, Composites Part A71:176–183
4. F. Morgeneyer, T. Taillandier-Thomas, L. Helfen, T. Baumbach, I. Sinclair, S. Roux, F. Hild (2014) In situ 3D observation of early strain localisation during failure of thin Al alloy (2198) sheet, Acta Mater. 69:78–91