Abstract
Sulci are localized furrows on the surface of soft materials that form by a compression-induced instability. We unfold this instability by breaking its natural scale and translation invariance, and compute a limiting bifurcation diagram for sulcfication showing that it is a scale-free, subcritical nonlinear instability. In contrast with classical nucleation, sulcification is continuous, occurs in purely elastic continua and is structurally stable in the limit of vanishing surface energy. During loading, a sulcus nucleates at a point with an upper critical strain and an essential singularity in the linearized spectrum. On unloading, it quasistatically shrinks to a point with a lower critical strain, explained by breaking of scale symmetry. At intermediate strains the system is linearly stable but nonlinearly unstable with no energy barrier. Simple experiments confirm the existence of these two critical strains.
- Received 20 August 2010
DOI:https://doi.org/10.1103/PhysRevLett.106.105702
© 2011 American Physical Society
Viewpoint
Folding furrows
Published 7 March 2011
Folds on the surface of soft materials are shown to be a consequence of a nonlinear instability.
See more in Physics