Oscillatory fracture paths
in thin elastic sheets

We report a novel mode of oscillatory crack propagation when a cutting tip is driven through a thin brittle film. Experiments show that the amplitude and wavelength of the oscillatory crack paths scale linearly with the width of the cutting tip over a wide range of length-scales but are independent of the width of the sheet and of the cutting speed. A geometric model is presented, which provides a simple but thorough interpretation of the oscillations.

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