Abstract

Snap-through buckling is a type of instability in which an elastic object rapidly jumps from one state to another. Such instabilities are familiar from everyday life: children’s popper toys rapidly ‘pop’ and jump after being turned inside-out, while snap-through is harnessed to generate fast motions in applications ranging from soft robotics to artificial heart valves. In biology, snap-through has long been exploited to convert energy stored slowly into explosive movements: both the leaf of the Venus flytrap and the beak of the hummingbird snap-through to catch prey unawares. Despite the ubiquity of snap-through in nature and engineering, its dynamics is usually only understood qualitatively, with many examples reported of delay phenomena in which snap-through occurs much more slowly than would be expected for an elastic instability. To explain this discrepancy, it is commonly assumed that some dissipation mechanism (such as material viscoelasticity) must be causing the system to lose energy and slow down. In this talk we examine how viscoelasticity influences the snap-through dynamics of a simple truss-like structure. We present a regime diagram that characterises when the timescale of snap-through is governed by viscous or elastic effects, and relate this to the creep behaviour we see in jumping popper toys.