Sébastien Neukirch
Institut Jean le Rond d'Alembert
Centre National de la Recherche Scientifique
Université Pierre et Marie Curie
Paris, France

tel: +33 1 44 27 72 61
fax : +33 1 44 27 52 59
e-mail: sebastien.neukirch (-atat-) upmc.fr

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Fragmentation of rods by cascading cracks: why spaghetti do not break in half

Basile Audoly and Sébastien Neukirch

Physical Review Letters, 95 (2005) 095505

Abstract : When thin brittle rods such as dry spaghetti pasta are bent beyond their limit curvature, they often break into more than two pieces, typically three or four. With the aim to understand these multiple breakings, we study the dynamics of a rod bent just below its limit curvature and suddenly released at one end. We find that the sudden relaxation of the curvature at the newly freed end leads to a burst of flexural waves, whose dynamics are described by a self-similar solution with no adjustable parameters. These flexural waves locally increase the curvature in the rod and we argue that this counter-intuitive mechanism is responsible for the fragmentation of brittle rods under bending. A simple experiment supporting the claim is presented.

PACS numbers : 62.20.Mk, 46.50.+a, 46.70.De

Key words : dynamics of elastic rods, self-similar solution

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