Special Physics Seminar

Elastic instabilities in soft solids:
Fingers, Beads, Sulci and Brains

John Biggins

Cambridge University

We are all familiar with the prototypical elastic instability: the buckling of a slender column under a compressive load. Soft elastic solids, such as rubbers, gels, and biological tissues, are united by their ability to sustain very large shape changes, and consequently undergo a range of more exotic elastic instabilities which sculpt the solids into complicated and unexpected shapes. In this talk I will discuss several such instabilities, including fingering in soft solid layers under tension, beading in solid cylinders subject to surface tension, and sulcus formation at the boundary of soft solids in compression. I will finish by discussing the growing body of evidence that evolution has harnessed these mechanical instabilities to sculpt organs during development, and, in particular, that mechanical buckling underpins the formation of the folds on the surface of the human brain.