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From:
G. Gutiérez (1,2), C. Colonnello (1), P. Boltenhagen (2,3), J. R. Darias (1), R. Peralta-Fabi (2,4), F. Brau (5), and E. Clément (2)
(1) Departamento de FÌsica, Universidad SimÛn BolÌvar, Apartado Postal 89000, Caracas 1080-A, Venezuela
(2) PMMH, ESPCI, CNRS (UMR 7636) and Université Paris 6 & Paris 7, 75005 Paris, France
(3) Université Rennes 1, Institut de Physique de Rennes (UMR UR1-CNRS 6251), Bat. 11A, Campus de Beaulieu, F-35042 Rennes, France
(4) Departamento de FÌsica, Facultad de Ciencias, Universidad Nacional AutÛnoma de MÈxico, 04510 Mexico
D.F., Mexico
(5) Nonlinear Physical Chemistry Unit, Université libre de Bruxelles (ULB), CP231, 1050 Brussels, Belgium “Silo collapse under granular discharge”, Physical Review Letters, Vol. 114, 018001, 6 January, 2015
DOI: http://dx.doi.org/10.1103/PhysRevLett.114.018001
ABSTRACT: We investigate, at a laboratory scale, the collapse of cylindrical shells of radius R and thickness t induced by a granular discharge. We measure the critical filling height for which the structure fails upon discharge. We observe that the silos sustain filling heights significantly above an estimation obtained by coupling standard shell-buckling and granular stress distribution theories. Two effects contribute to stabilize the structure: (i) below the critical filling height, a dynamical stabilization due to granular wall friction prevents the localized shell-buckling modes to grow irreversibly; (ii) above the critical filling height, collapse occurs before the downward sliding motion of the whole granular column sets in, such that only a partial friction mobilization is at play. However, we notice also that the critical filling height is reduced as the grain size d increases. The importance of grain size contribution is controlled by the ratio d/sqrt(Rt). We rationalize these antagonist effects with a novel fluid-structure theory both accounting for the actual status of granular friction at the wall and the inherent shell imperfections mediated by the grains. This theory yields new scaling predictions which are compared with the experimental results.
In the url
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.018001
the authors write the caption of Fig. 1:
"Experimental setup and buckling sequence: (a) Picture of the experimental apparatus showing a paper silo, and the two mirrors used for complete visualization of the discharge. (b) Schematic cross section of the silo with its dimensions. (c)–(f) Time sequence of deformations in a collapsing silo during grain discharge. Glass beads d=1.5±0.1 mm, column thickness t=27±5 μm, and R=D/2=2.00±0.05 cm."
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