Investigating shock processes in bimodal powder compaction through modelling and experiment at the mesoscale

INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES

卷:163

Article

Derrick, James G.¹  Rutherford, Michael E.²  Chapman, David J.^2,3  Davison, Thomas M.¹  Duarte, Joao Piroto P.³  Farbaniec, Lukasz³  Bland, Phil A.⁴  Eakins, Daniel E.^2,3  Collins, Gareth S.¹ 

[1] Imperial Coll London, Dept Earth Sci & Engn, London SW7 2BP, England

[2] Univ Oxford, Dept Engn Sci, Solid Mech & Mat Engn, Oxford OX1 3PJ, England

[3] Imperial Coll London, Blackett Lab, Inst Shock Phys, London SW7 2BW, England

[4] Curtin Univ, Dept Appl Geol, GPO Box 01987, Perth, WA 6845, Australia

关键词: Mesoscale modelling;    Impact;    Shock compaction;    Heterogeneous;    Chondritic meteorites;    X-ray radiography;    Granular media;   

DOI  :  10.1016/j.ijsolstr.2018.12.025

来源: Elsevier

【 摘 要 】

Impact-driven compaction is a proposed mechanism for the lithification of primordial bimodal granular mixtures from which many meteorites derive. We present a numerical-experimental mesoscale study that investigates the fundamental processes in shock compaction of this heterogeneous matter, using analog materials. Experiments were performed at the European Synchrotron Radiation Facility generating realtime, in-situ, X-ray radiographs of the shock's passage in representative granular systems. Mesoscale simulations were performed using a shock physics code and set-ups that were geometrically identical to the experiments. We considered two scenarios: pure matrix, and matrix with a single chondrule. Good agreement was found between experiments and models in terms of shock position and post-shock compaction in the pure powder setup. When considering a single grain embedded in matrix we observed a spatial porosity anisotropy in its vicinity; the compaction was greater in the region immediately shockward of the grain, and less in its lee. We introduced the porosity vector, C, which points in the direction of lowest compaction across a chondrule. This direction-dependent observation may present a new way to decode the magnitude, and direction, of a single shock wave experienced by a meteorite in the past (C) 2019 Elsevier Ltd. All rights reserved.

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