Time: 16.00 - 17.00hours (drinks afterwards)
abstract
When acted on by external forces, sheets tend to bend out of plane rather than stretch. For weak forcing, this leads to the distinctive wrinkling instabilities that you see on your skin. When more strongly confined, sheets crumple, and condense stress into a network of ridges which confer rigidity on the bulk material. At even stronger forcing, these ridges develop into plastic creases with complex time‐dependent mechanical properties. This
sequence of morphologies is seen at a variety of scales in the natural world, ranging from folds on the earth?s crust, to the wavy shapes of leaves, down to more microscopic biomembranes and synthetic thin films. I will describe experiments that study representative examples of this progression of features, concentrating mainly on wrinkling patterns seen in ultrathin polymer films supported on fluid surfaces.