In-situ visualization of dynamic fracture and fragmentation of an L-type ordinary chondrite by combined synchrotron X-ray radiography and microtomography

1,2Lukasz Farbaniec,1,2David J.Chapman,1Jack R.W.Patten,2Liam C.Smith,3James D.Hogan,4Alexander Rack,1,2Daniel E.Eakins
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114346]
1Institute of Shock Physics, Imperial College London, London SW7 2AZ, UK
2Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK
3Department of Mechanical Engineering, University of Alberta, Edmonton, AB T6G2R3, Canada
4European Synchrotron Radiation Facility, CS40220, 38043 Grenoble Cedex 9, France
Copyright Elsevier

The relationship between the dynamic mechanical properties of stony meteorites and their microstructures was investigated in-situ for an L-type ordinary chondrite using a split-Hopkinson pressure bar apparatus and ultra-high speed phase-contrast X-ray radiography at the European Synchrotron Radiation Facility (ESRF). Synchrotron X-ray microtomography (CT) was performed both prior to and immediately following dynamic compression to correlate key structural features between the initial microstructure and recovered fragments as well as to identify the leading mechanisms for fracture and fragmentation. Real-time visualization of damage evolution in the specimens revealed the very first cracks to be initiated at the sites of FeNi-metal nodules. These cracks propagated rapidly through the largest group of chondrules (the porphyritic olivine type chondrules) along the loading direction, which led to the formation of column-like fragments. CT analysis of the collected fragments confirmed the dominant mode of fracture to be transgranular with a clear link between FeNi-metal nodule statistics and the size distribution of fragments, emphasizing their role in mechanical failure and fragmentation process. The resulting fragmentation was used to validate the predictions of brittle fragmentation models, and found to be in good agreement with the laboratory-scale impacts. In turn, these models can help unravel the consequences of impact-induced fragmentation processes that have helped shape the solar system.

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