Dominic Emery
School of Computing and Mathematics
Non-linearly elastic creasing
Creases are widespread in physiology and nature . For instance , they may be observed on surface of the brain , a contorted elephants trunk and in many soft foods and gels under stress . They have also been shown to drastically influence cell behaviours such as differentiation and migration in-vitro . Until very recently , the theoretical nature of elastic creasing as a bifurcation phenomenon was shrouded in mystery . This was predominantly due to its confusion with periodic instabilities such as wrinkling . Whereas wrinkles constitute a non-local sinusoidal surface displacement , creases are by definition a localisation of material self contact on a materials free surface . We show here that the bifurcation condition for creasing in terms of a general strain-energy function can be sought by matching an ``outer " uniform compression solution , an ``inner " infinitesimal creased solution and an ``intermediate " incremental displacement field through a conservation law of energy and momentum . Critical compression ' s for the onset of creasing are presented for the neo-Hookean and Gent strain energy functions .
Postgraduate Conference 2020 Page 20