Folding and crumpling of thin elastic sheets: statistical analyses of geometrical and energetical properties

November 28 2008
Types d’événements
Séminaire SPCSI
Stéphanie Deboeuf
SPEC Bât 466 p.111 (1er ét.)
Configuration de la salle en séminaire ou réunion
30 places
Vidéo Projecteur
28/11/2008
from 11:00

DNA packaging in viral capsids, or plant leaves growing in buds, are some examples of close-packed low dimensional biological structures. We study the purely mechanical counterparts, such as folded rods and crumpled sheets. I will present our results about geometrical and energetical properties of an elastic sheet, in two compaction experiments. The first experiment consists of pulling a circular polyester sheet from its center through a smaller rigid hole acting as a container (quasi-2d compaction). In this geometry, it is possible to simultaneously record the applied force and observe the folded configurations. Despite the wide variety of possible folded patterns, related to a very complex energetical landscape, elementary patterns are identified, whose geometrical properties and elastic energy, are directly measured. The second experiment consists of crumpling by hand a paper sheet (3d compaction). Geometrical properties are measured in the folded configurations. Characteristic length-scales of these crumpled 3d-networks are extracted and compared with other studies from the literature. Our results suggest to focus on these elementary patterns (like “particles”), in order to understand “thermal equilibration“ in close-packed systems, and microscopic distributions of energy, by means of statistical physics tools.

Laboratoire PMMH, ESPCI