Nonlinear deformation of thin-walled structures for deployable and morphing applications

This PhD project concerns the nonlinear deformation of thin-walled structures for deployable and morphing applications. Previous research has identified two notable elements; so-called "tape-springs" and corrugated sheets. Both are familiar in everyday life, as tape-measures and as roofing elements, respectively. If they are made to be sufficiently thin, they can buckle elastically and deform in a localised manner; and if pre-stressed (by means of plastic working), they can be bistable, tristable or even neutrally stable in their deformed states. This project aims to explore generalised versions of tape-springs and corrugated sheets. The first aspect proposes to make a "tape-ring" - instead of being straight, the tape curves around to form a ring, resulting in an open toroidal shape. Preliminary finite element analysis by Seffen has established that a tape-ring buckles in the same way as a tape-spring but forms two creases, which can then travel around the ring, enabling a type of zero-stiffness spinning action. The project will then consider how to interconnect tape-rings as repeating planar units, in order to form a plate with local texture and holes. It is surmised that the interacting units will proffer unusual and novel, large deformations of the plate overall. The project will combine experiments, manufacturing, computational study and mathematical analysis. This project falls within the Structural Engineering research area.