Giving a Cork a Mathematical Twist

October 9, 2007

Well, now we know: It takes less effort to remove a cork from a bottle by pulling and twisting than by just pulling it. The evidence appears in a 15-page mathematical paper published recently in the Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences.

Modeling a cork as an "incompressible rubber-like material," Michel Destrade of the Université Pierre et Marie Curie in Paris, along with mathematician Riccardo de Pascalis and engineer Giuseppe Saccomandi (both from the University of Lecce, in Italy), showed that a cork being pulled from a bottle can twist internally. Adding your own twist to this "secondary deformation" makes the task that much easier.

Their paper, titled "The stress field in a pulled cork and some subtle points in the semi-inverse method of nonlinear elasticity," shows that solids can deform in counterintuitive ways. As reported in Science, applied mathematician Cornelius Horgan of the University of Virginia called the researchers' analysis a "very nice application of the theory of nonlinear elasticity."

We'll drink to that!

Source: Science, Aug. 31, 2007; Telegraph, Aug. 22, 2007.