Diffusion stimulated snap-through inversion of an elastic hemispherical shell

Abstract

Vigorous snap-through buckling instability of shell structures is adopted by a variety of biological (Venus flytrap, Sphaerobolus) and artificial systems (jumping popper) as an efficient strategy for rapid transmutation between different geometrical configurations. Here we explore the snap-through buckling inversion of an elastomeric bilayer shell stimulated by diffusion induced differential swelling. Hemispherical bilayer shells of two different elastomers are fabricated layer-by-layer by pour coating on acrylic molds. The prepared shells are then fully immersed in organic solvents to swell. We characterize the dynamics of snap-through inversion through total response time and energy released, using both an analytical elastic energy model and Abaqus simulations. Upon combining our theory with experiments of various geometry of thin shells, we suggest a novel model for snap-through inverting shells for both biologists and toy enthusiasts.