Department of Engineering / Profiles / Dr John Biggins

Department of Engineering

Dr John Biggins

jsb56

University Lecturer in Applied Mechanics

Academic Division: Mechanics, Materials and Design

Telephone: +44 1223 7 60502

Email: jsb56@eng.cam.ac.uk

Personal website

Publications


Research interests

Novel elastic instabilities

Soft solids can undergo shape changes of several hundred percent. This introduces non-linearities into their description that result from the geometry of large deformations, and hence which are universal to all soft solids. These non-linearities can drive elastic instabilities, resulting in simple loads producing complicated shape changes. I work on the theory of these shape changes. Recent successes have included a description of an elastic instability akin to viscous fingering that occurs when a fluid is pumped into a soft elastic layer in a Hele-Shaw cell, and the description of the pattern sulci form in on the two-dimensional compressed surface of a soft solid.

Elastic instabilities that sculpt biological organs

When we see a complicated shape in biology - for example, the folds of the human brain - we typically think the development must be the result of a carefully regulated chemical process, with a Turing-like reaction diffusion instability at the heart of the pattern generation mechanism. This way of thinking fits easily into a biochemistry mindset dominated by genes and proteins, but sometimes things are simpler. I am interested in examples where the biological growth is very simple but the action of mechanical forces (i.e. elasticity) sculpts the tissue into the observed complex shape. For example, in a recent paper we argue that the folds on the human brain are a simple mechanical consequence of the outside of the brain (the cerebral cortex) growing faster than the inside of the brain, and then being shaped by a sulcus forming compressive elastic instability akin to buckling and wrinkling. An example of the brain-like shapes this mechanism can produce is shown on the right.

Other interests

I have worked on the theoretical description of liquid crystal rubbers, in particular, on the peculiarly soft response of polydomain nematic rubber, and the microstructures in SmC rubbers.

I also explained the chain fountain.

Department role and responsibilities