Title: Friction-induced sheet nacre fracture: effects of nano-shocks on cracks location

Authors: Philippe Stempfle, Olivier Pantale, Richard Kouitat Njiwa, Marthe Rousseau, Evelyne Lopez, Xavier Bourrat

Addresses: Laboratoire Genie de Production, ENIT, 47 Avenue d'Azereix, 65016 TARBES Cedex, France. ' Laboratoire Genie de Production, ENIT, 47 Avenue d'Azereix, 65016 TARBES Cedex, France. ' Laboratoire Science et Génie des Surfaces, Ecole des Mines, Parc de Saurupt, 54042 NANCY Cedex, France. ' Museum National d'Histoire Naturelle (UMR 5178 CNRS –– MNHN), CP26, 43 Rue Cuvier, 75005 PARIS, France. ' Museum National d'Histoire Naturelle (UMR 5178 CNRS –– MNHN), CP26, 43 Rue Cuvier, 75005 PARIS, France. ' Institut des Sciences de la Terre d'Orleans CNRS, 1A Rue de la Ferollerie, 45071 ORLEANS Cedex 2, France

Abstract: Nacre (the pearly internal layer of molluscan shells) is an attractive nanocomposite displaying high mechanical properties, low density and a good biocompatibility with human bones. It is currently studied for both the prosthesis design and the creation of new organic/inorganic hybrid materials by mimicking biomineralisation processes. These exceptional mechanical properties are ascribed to its highly ordered layered |bricks and mortar| microstructure and more particularly to the energy absorption ability of the mortar during crack propagation. However, this ability appears to be drastically reduced in presence of nano-shocks generated during friction by the dynamic solicitations. This paper compares two Finite Element simulations – a quasi-static compression test and a dynamic impact test – in order to consider the fracture mechanisms induced by friction. It reveals that cracks migrate from the mortar to the bricks, involving in the latter case, the formation of wear nano-debris. These numerical results are confronted with experimental results during friction.

Keywords: sheet nacre fracture; friction; nanowear; nanoindentation; numerical simulation; dynamic impact tests; nanoshocks; crack location; nanocomposites; nanotechnology; biomineralisation; microstructure; energy absorption; crack propagation.

DOI: 10.1504/IJNT.2007.015466

International Journal of Nanotechnology, 2007 Vol.4 No.6, pp.712 - 729

Published online: 18 Oct 2007 *

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