Synchrotron and neutron laminography for three-dimensional imaging of devices and flat material specimens

Abstract

International audienceComputed laminography has been introduced to synchrotron and neutron imaging set-ups to complement computed tomography for three-dimensional imaging of laterally extended (i. e. plate-like) specimens. The wide application field of computed laminography due to different contrast modes (X-ray or neutron absorption and X-ray phase contrast) and spatial resolutions ranging from some 100 down to approximately 0.5 μm is demonstrated. Selected examples from device inspection and from materials science are reported. They outline the interest of the method for nondestructive and in-situ measurements of regions of interest in large planar specimens where engineering-relevant boundary conditions have to be met. With a materials science background, the in-situ investigation of crack propagation in aluminium sheets and carbon-fibre composite panels under mechanical loading is reported

In situ laminography study of three-dimensional individual void shape evolution at crack initiation and comparison with Gurson–Tvergaard–Needleman-type simulations

“…Therefore, the technique is not well suited to in situ measurements of a plate-like specimen, i.e. extended in two directions and thin in the third one [19,20]. Moreover, plastic zone sizes in the specimens for CT are not compatible with many key engineering failure situations where plastic zone sizes may reach the order of several millimetres.…”

“…Moreover, plastic zone sizes in the specimens for CT are not compatible with many key engineering failure situations where plastic zone sizes may reach the order of several millimetres. With the recent progress in synchrotron laminography [19,20] it has become possible to observe in situ and in three dimensions damage evolution in plate-like objects [21]. Ductile crack initiation and propagation in a 2139 Al alloy have been studied for the first time in three dimensions and in situ inside a thin (1.0 mm thickness) sheet material with boundary conditions close to those of structures in service and close to standard mechanical tests to assess the tearing resistance [22].…”

Slant strained band development during flat to slant crack transition in AA 2198 T8 sheet: in situ 3D measurements

“…Only stopped cracks could be cut-out and assessed in 3D by tomography at micrometer resolution. This limitation is overcome by resorting to synchrotron radiation computed laminography (Helfen et al 2005(Helfen et al , 2009Altapova et al 2012) that provides the opportunity to assess in situ damage processes in laterally extended sheet-like specimens using physical boundary conditions of engineering relevance and associated naturally developing plastic zone sizes of the order of several millimeters (Morgeneyer et al 2011;Helfen et al 2012;Shen et al 2013). As such, it complements tomographic analyses.…”

Experimental-Numerical Validation Framework for Micromechanical Simulations

“…• X-ray laminography, which is a non-destructive 3D imaging technique for laterally extended 3D objects [26,27,28,29,30], to acquire radiographs and subsequently reconstruct 3D volumes of different steps of a mechanical test. By post-processing such bulk data, the morphology of the two-phase microstructure can be revealed and its changes can be analyzed.…”