Modular Design of Multistable Pneumatic Structures from a Flat Pattern of Air Pouches

We introduce a novel family of structures that can be inflated from a plane to form a three-dimensional surface using articulated straight pouches with inextensible membranes. Specifically, we propose a modular design using a quadrangle surrounded by four slender pouches, whose inflation causes the surface to form a saddle shape. Then we show a fabrication method using heated nylon films with heat adhesives separated by paper mask patterns inside. We first show a geometric model to explain and predict the out-of-plane deformation and the bi-stability effect inherited in this structure. Through a geometric analysis and an elastic simulation of a pouch, we show that lowering the width-length ratio of pouches reduces the imperfection of shapes. We further propose a method for controlling the height of saddles using concentric patterns. We then extend structural modules into multiple-grid systems and identify the multistable behaviors of the overall structure.