Pascal Damman
Professeur, Laboratoire interface et fluides complexes, Université de Mons, Belgique

“Pattern formation through elastic instabilities”

Complex shapes and patterns spontaneously emerge through the application of constraints on elastic materials. Slender objects: plates, rods and shells subjected to internal or external stresses become rapidly unstable and form complex patterns of folds and wrinkles. Far from the threshold, these patterns are strongly impacted by nonlinearities, which generate a focalization of deformation in a single fold or the puzzling observation of period-doubling bifurcations. Through this work, we have highlighted a new concept: elastic morphogenesis, based on the use of geometric constraints. For example, fold cascades (curtains) geometrically prevent the focalization mechanism, whereas the focus of the folds is favored in twisted ribbons.