%0 Journal Article %T Selection of hexagonal buckling patterns by the elastic Rayleigh-Taylor instability %+ Department of Chemical and Biomolecular Engineering %+ Laboratoire de Mécanique et Génie Civil (LMGC) %+ Physique et Mécanique des Milieux Divisés (PMMD) %+ Laboratoire Charles Coulomb (L2C) %+ Department of Mathematics [University of Arizona] %+ California Institute of Technology (CALTECH) %+ Laboratoire de mécanique des solides (LMS) %A Chakrabarti, Aditi %A Mora, Serge %A Richard, Franck %A Phou, Ty %A Fromental, Jean-Marc %A Pomeau, Yves %A Audoly, Basile %< avec comité de lecture %@ 0022-5096 %J Journal of the Mechanics and Physics of Solids %I Elsevier %V 121 %P 234 - 257 %8 2018-07-30 %D 2018 %R 10.1016/j.jmps.2018.07.024 %K Plates %K Stability and bifurcation %K Elastic material %K Finite strain %K Buckling %Z Engineering Sciences [physics]/Mechanics [physics.med-ph]/Solid mechanics [physics.class-ph]Journal articles %X We investigate the non-linear buckling patterns produced by the elastic Rayleigh-Taylor instability in a hyper-elastic slab hanging below a rigid horizontal plane, using a combination of experiments, weakly non-linear expansions and numerical simulations. Our experiments reveal the formation of hexagonal patterns through a discontinuous transition. As the unbuckled state is transversely isotropic, a continuum of linear modes become critical at the first bifurcation load: the critical wavevectors form a circle contained in a horizontal plane. Using a weakly non-linear post-bifurcation expansion, we investigate how these linear modes cooperate to produce buckling patterns: by a mechanism documented in other transversely isotropic structures, three-modes coupling make the unbuckled configuration unstable with respect to hexagonal patterns by a transcritical bifurcation. Stripe and square patterns are solutions of the post-bifurcation expansion as well but they are unstable near the threshold. These analytical results are confirmed and complemented by numerical simulations. %G English %2 https://hal.science/hal-01869797/document %2 https://hal.science/hal-01869797/file/Art_Mora_al_J.Mech.Phys.Sol._2018.pdf %L hal-01869797 %U https://hal.science/hal-01869797 %~ X %~ INSTITUT-TELECOM %~ CNRS %~ LMGC %~ X-LMS %~ X-DEP %~ X-DEP-MECA %~ PARISTECH %~ L2C %~ UNIV-PARIS-SACLAY %~ X-SACLAY %~ MIPS %~ UNIV-MONTPELLIER %~ UM-2015-2021