Harnessing stiffness asymmetry in thin sheets inflatables for high deformation shape morphing

Inflatables are particularly popular in the field of shape morphing materials. Their simple, purely mechanical actuation allows for fast deployment and high reusability. Moreover, just as the structural stiffness of a party balloon is directly linked to its inside pressure, inflatable objects offer an elegant example of the coupling of elasticity and geometry.

In this presentation, we focus on the inflation of a network of tubes presenting two sides of distinct stiffness. The showcased objects are indeed made by welding two sheets of different mechanical properties. Upon inflation, a tube will overall bend towards its stiffer side similarly to the well-studied bilayer effect. Such deformations allow for enormous deformations across large networks. We present experimental results on the mechanics of inflation of either one or several connected tubes.

Afterwards we formulate and solve an inverse problem to design a wide variety of objects that can be described as a two-dimensional curve perpendicularly to the direction of the tubes. The question of the stiffness of such structures is discussed as well. We finally present several applications of asymmetric tubular inflatables to more complex geometries: axisymmetric surfaces, kirigami, and curved folding.