Quand :
18 mars 2024 @ 11:30 – 12:30
2024-03-18T11:30:00+01:00
2024-03-18T12:30:00+01:00
Où :
Bâtiment Condorcet
454 A

Monday, March 18th, 11h30, Room 454 A, Condorcet Building.

Paul Baconnier

AMOLF, Physics of functional complex matter,

Amsterdam, The Netherlands,

Active elastic solids – a classification for collective actuations

Active solids consist of elastically coupled out-of-equilibrium units performing work. They are central to autonomous processes in biological systems, e.g. locomotion, self-oscillations and morphogenesis. Yet, the feedback mechanism between elastic and active forces, and the possible emergence of collective behaviors in such systems remain poorly understood. We take advantage of centimetric models of self-propelled active units and introduce a minimal realization of an active elastic solid. Polar active agents exert forces on the nodes of a two-dimensional elastic lattice, and the resulting displacement field nonlinearly reorients the active agents. >From this so-called elasto-active feedback emerges numerous new collective behaviors, which shall be called collective actuation.

In this talk, I will show how the structure’s vibrational properties control the emergence and the properties of collective actuation. Crucially, collective actuation is selective: only a few normal modes are activated by the active dynamics, and they are not necessarily the lowest energy ones. Combining experiments with the numerical and theoretical analysis of an agents model, we unveil the bifurcation scenario and the selection mechanism by which the collective actuation takes place. Eventually, we propose a classification of collective actuations, and draw analogies with the self-oscillating behaviors observed in living active solids, such as cell monolayers and bacterial bio-films.

Work performed in collaboration with O. Dauchot (Gulliver, UMR 7083, PSL)

À lire aussi

Formation de singularités en érosion par dissolution

Formation de singularités en érosion par dissolution

En s’écoulant sur des roches solubles, l’eau peut créer dans la nature des motifs remarquables, qui présentent souvent des pointes acérées. Les coups de gouge, dépressions concaves entourées de crêtes, en sont un exemple commun. En combinant mesures de terrain, modèle...

La mécanique des plantes grimpantes décryptée

La mécanique des plantes grimpantes décryptée

On a vu récemment fleurir des parasols végétaux sur les parvis de gare de la capitale (et ailleurs). Une structure ressemblant à un parapluie a été conçue pour soutenir et guider la croissance de la plante, de manière à ce qu'elle puisse pousser afin de créer un îlot...