Happy to be part of the third workshop of the Center for Complexity & Biosystems, University of Milan, with a broad interdisciplinary scope.
It has been a very long work, beautifully leaded by Alexandre the great, but finally it’s out there: the preprint of our review article on elastoplastic models for the deformation of amorphous solids. Since we begin a long edition path now, any comments and suggestions would be welcome! Enjoy! (arxiv:1708.09194)
I had had the pleasure to be in Napoli giving a seminar at the Physics Department of the University of Naples Federico II, followed by very interesting discussions with colleagues that showed up for the occasion. I would like to thank all of them and specially my host in this visit and good friend Raffaele Pastore for such a wonderful time in the adoptive city of Diego Armando 🙂 .
(edited) Our article is now available online in Phys. Rev. Lett. !
In presence of impurities, ferromagnetic and ferroelectric domain walls slide only above a finite external field. Close to this depinning threshold, they proceed by large and abrupt jumps, called avalanches, while, at much smaller field, these interfaces creep by thermal activation. In this work we develop a novel numerical technique that captures the ultra-slow creep regime over huge time scales. We point out the existence of activated events that involve collective reorganizations similar to avalanches, but, at variance with them, display correlated spatio-temporal patterns that resemble the complex sequence of aftershocks observed after a large earthquake. Remarkably, we show that events assembly in independent clusters that display at large scales the same statistics as critical depinning avalanches. We foresee this correlated dynamics being experimentally accessible by magneto-optical imaging of ferromagnetic films.
In this paper, with Kamran Karimi and Jean-Louis Barrat, we solve numerically the dynamics of an amorphous solid under deformation in the quasistatic driving limit, by means of a finite elements technique. We study the noise statistics of the stress-strain signal in the steady state plastic flow, focusing on systems with low internal dissipation. We analyze the distributions of avalanche sizes and durations and the density of shear transformations when varying the damping strength. In contrast to avalanches in the overdamped case, dominated by the yielding point universal exponents, inertial avalanches are controlled by a non-universal damping dependent feedback mechanism; eventually turning negligible the role of correlations. Still, some general properties of avalanches persist and new scaling relations can be proposed.
It will be available soon in PRE.
Few weeks ago I had the pleasure to participate at the 8th Multiscale Materials Modeling (MMM) international conference in Dijon, France, where I presented our work on the avalanche statistics near the yielding transition. It was a week full of interesting discussions and new motivating ideas. Thanks to the symposium D organizers for the opportunity.