Designing inflatable shells using unstructured meshes

Abstract We propose a method for designing inflatable shells made of superimposed quasi‐inextensible membranes sealed according to specific welding patterns. The shapes of the patterns are defined on unit triangular cells and allow us to locally control the contraction of the cells from rest to inflated configuration. By paving the patterns on the surface of the structure and properly grading their parameters, we are able to generate inflatables of prescribed deployed shapes through metric frustration. Our triangular cells exhibit isotropic contraction. Our inverse design algorithm can thus leverage conformal parametrization to compute local contraction ratios that are converted to pattern geometries. Key to our approach is to define the arrangement of the patterns using an unstructured triangulation of the target surface. Compared to more traditional arrangements laid out on regular grids, our approach allows us to easily cut or segment the structure without visible seams and to decrease the contraction range necessary to reproduce a given surface, thus enlarging our design space. Additionally, unstructured arrangements lead to inflatable structures whose cells conform to the boundary of the target surface and therefore better covers it. We demonstrate the capabilities of our approach in simulation and by fabricating various prototypes, made of one or multiple components.