Strain accommodation in kinking nonlinear elastic solids

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• Professor Michel W Barsoum, Department of Materials Science and Engineering, Drexel University
• Friday 30 October 2015, 14:00-15:00
• Cambridge University Engineering Department, LR4.

If you have a question about this talk, please contact Ms Helen Gardner.

Please note that this is a Mechanics Colloquium and is in LT4

A decade or so ago we have identified a large class of solids that we characterized as kinking nonlinear elastic, KNE , because the deformation is elastic but nonlinear, and, in most cases, is accompanied by kink bands and/or kink boundaries. The signature of KNE solids is the formation of fully, and spontaneously, reversible hysteretic stress-strain loops. The energy dissipated per cycle can sometimes be substantial and increases rapidly with applied stress. For example, Ti3SiC2 – a MAX phase – can be cyclically compressed to stresses of the order of 1 GPa, while dissipating 25 % of the energy during each cycle. In this talk I will review the evidence – which includes TEM , nanoindentation, in situ neutron diffraction, EBSD among others – for kinking non-linear elasticity in a large variety of solids, including the MAX phases, hexagonal metals, mica, LiNbO3, sapphire, graphite, ZnO, among others. I will also propose a number of possible micromechanisms that can be invoked to explain this unusual mechanical response, including a new micromechanism that is distinct from dislocations. Given that a sufficient condition for a solid to be KNE is plastic anisotropy – i.e. the confinement of the deformation to 2D – it follows that KNE solids are quite ubiquitous indeed, while remaining under-appreciated.

Short Bio

Prof. Michel W. Barsoum – Distinguished Professor in the Department of Materials Science and Engineering at Drexel University – is an internationally recognized leader in the area of MAX phases. He is the author of two entries on the MAX phases in the Encyclopedia of Materials Science and the book, MAX Phases, published in 2013 by Wiley-Verlag. He is also the author of Fundamentals of Ceramics, a leading textbook in his field. In 2011, he and Drexel colleagues selectively etched the A-group layers from the MAX phases to produce an entirely new family of 2D solids – they labeled MXenes – that have sparked global interest because of their potential in many applications, least of which is energy storage. With over 350 refereed publications, and a ISI h index of 58, his work has been highly cited. He is a fellow of the American Ceramic Society and the World Academy of Ceramics. In 2000 he was awarded a Humboldt-Max Planck Research Award for Senior US Research Scientists. Since 2008 he has been a visiting professor at Linkoping University in Sweden. He is currently spending part of his sabbatical year funded at Imperial College in London, funded in part by the Leverhulme Trust.

This talk is part of the Engineering - Mechanics and Materials Seminar Series series.

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