Finite axisymmetric deformations of liquid-amplified electrostatic zipping structures for shape displays

Active shape morphing surfaces, that generate shape geometries through actuation, are an expanding field of soft robotics and have great potential for applications in haptic feedback, information displays, aerodynamics, and more. Liquid amplified electrostatic zipping actuation is a favorable candidate for morphing surfaces due to its fast response, low power consumption and considerable force output. Here, we propose an axisymmetric liquid amplified electrostatic zipping structure, containing a convex rigid electrode and an elastic film-electrode as morphing surfaces. A modeling method is developed for the deformation of the film-electrode, by combining the non-linear elasticity theory and energy minimum principle. We find numerically and experimentally that wrinkling may occur at the kink of the deformed film-electrode. A relaxed strain energy function is adopted to consider the tensed and wrinkled regions. This model allows us to better understand the impact of applied voltage, material, geometry, and even film pre-stretching on the quasi-static behavior of the film-electrode. The effects of non-dimensional voltage, rigid electrode radius and aspect ratio, and film pre-stretch are discussed. The experimental validation of this model is presented. Finally, we preliminarily demonstrate that the proposed shape morphing surface is used for information displays.