Ref HAL: hal-01101059_v1
DOI: 10.1103/PhysRevLett.113.178301
WoS: 000344052700015
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51 Citations
Résumé:

We demonstrate the instability of the free surface of a soft elastic solid facing downwards. Experiments are carried out using a gel of constant density rho, shear modulus mu, put in a rigid cylindrical dish of depth h. When turned upside down, the free surface of the gel undergoes a normal outgoing acceleration g. It remains perfectly flat for rhogh/mu

Ref HAL: hal-00842852_v2
DOI: 10.1103/PhysRevLett.111.114301
WoS: 000324233400011
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66 Citations
Résumé:

Under the effect of surface tension a blob of liquid adopts a spherical shape when immersed in another fluid. We demonstrate experimentally that soft, centimeter-size elastic solids can exhibit a similar behavior: when immersed into a liquid, a gel having a low elastic modulus undergoes large, reversible deformations. We analyze three fundamental types of deformations of a slender elastic solid driven by surface stress, depending on the shape of its cross-section: a circular elastic cylinder shortens in the longitudinal direction and stretches transversally; the sharp edges of a square based prism get rounded off as its cross-sections tend to become circular; a slender, triangular based prism bends. These experimental results are compared to analysis and non-linear simulations of neo-Hookean solids deformed by surface tension, and are found to be in good agreement with each other.

PMID 23005837
DOI: 10.1103/PhysRevE.86.026119
WoS: 000308133400002
16 Citations
Résumé:

When a very flexible wire is dipped into a soapy solution, it collapses onto itself. We consider the regions of high curvature where the wire folds back onto itself, enclosing a capillary film. The shapes of these end loops are measured in experiments using soap films and compared to a known similarity solution. The sizes of these structures provide a simple and reliable way to measure surface tension.

Résumé:

We report observation of Plateau instability in a thin filament of solid gel with a very small elastic modulus. A longitudinal undulation of the surface of the cylinder reduces its area thereby triggering capillary instability, but is counterbalanced by elastic forces following the deformation. This competition leads to a nontrivial instability threshold for a solid cylinder. The ratio of surface tension to elastic modulus defines a characteristic length scale. The onset of linear instability is when the radius of the cylinder is one sixth of this length scale, in agreement with theory presented here.

PMID 21231307
DOI: 10.1103/PhysRevLett.105.214301
WoS: 000284308500011
170 Citations
Résumé:

We report observation of Plateau instability in a thin filament of solid gel wit h a very small elastic modulus. A longitudinal undulation of the surface of the cylinder reduces its area thereby triggering capillary instability, but is count erbalanced by elastic forces following the deformation. This competition leads t o a nontrivial instability threshold for a solid cylinder. The ratio of surface tension to elastic modulus defines a characteristic length scale. The onset of l inear instability is when the radius of the cylinder is one sixth of this length scale, in agreement with theory presented here.

Ref HAL: hal-00495624_v1
Ref Arxiv: 1006.5527
DOI: 10.1039/c0sm00155d
WoS: 000283155300036
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
26 Citations
Résumé:

We use Photon Correlation Imaging, a recently introduced space-resolved dynamic light scattering method, to investigate the spatial correlation of the dynamics of a variety of jammed and glassy soft materials. Strikingly, we find that in deeply jammed soft materials spatial correlations of the dynamics are quite generally ultra-long ranged, extending up to the system size, orders of magnitude larger than any relevant structural length scale, such as the particle size, or the mesh size for colloidal gel systems. This has to be contrasted with the case of molecular, colloidal and granular ``supercooled'' fluids, where spatial correlations of the dynamics extend over a few particles at most. Our findings suggest that ultra long range spatial correlations in the dynamics of a system are directly related to the origin of elasticity. While solid-like systems with entropic elasticity exhibit very moderate correlations, systems with enthalpic elasticity exhibit ultra-long range correlations due to the effective transmission of strains throughout the contact network.