Oscillatory fracture pathsSimulation based on our geometrical model. At each timestep, the convex hull, shown in grey, of the (crack path) union (the trace of the tool in the film's plane) is used to determine whether the crack advances and in which direction. This model, described in our latest preprint, is based on an estimate of the elastic energy of the film, and on Griffith's criterion for crack propagation. Although very simple, this model reproduces all the salient features of the experiments: non-smooth, oscillatory crack path, with periodic sharp changes in propagation direction (kinks), alternation of quasi-static propagation with periodic bursts of dynamic propagation.
in thin elastic sheets