Sommaire:

Rigidity is the hallmark of solids. It manifests itself as a resistance to flow: for small applied strain, solids provide an elastic, restoring, reversible response, as opposed to liquids. However, for large enough strain, irreversible plastic flow occurs at the so-called yielding point. Recently, yielding of crystals has been rationalised within a nucleation framework, suggesting that a rigid solid is always metastable to an infinitesimal deformation [1]. I shall revisit these topics presenting a recent numerical work exploring the metastability of oscillatory sheared crystals in three dimensions [2]. The main finding is that a transition from a reversible to an irreversible driving regime occurs and that it is affected by the specific composition and structure of the crystal. For large enough oscillation frequency, a yielding pattern reminiscent of spinodal decomposition emerges, consistent with the recent nucleation scenarii.

[1] P. Nath et al. PNAS 115, E4322 (2018)
[2] É. Brillaux and F. Turci, Soft Matter 15, 4371 (2019)

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