Rapid deployment of curved surfaces via programmable auxetics

Abstract

Deployable structures are physical mechanisms that can easily transition between two or more geometric configurations; such structures enable industrial, scientific, and consumer applications at a wide variety of scales. This paper develops novel deployable structures that can approximate a large class of doubly-curved surfaces and are easily actuated from a flat initial state via inflation or gravitational loading. The structures are based on two-dimensional rigid mechanical linkages that implicitly encode the curvature of the target shape via a user-programmable pattern that permits locally isotropic scaling under load. We explicitly characterize the shapes that can be realized by such structures---in particular, we show that they can approximate target surfaces of positive mean curvature and bounded scale distortion relative to a given reference domain. Based on this observation, we develop efficient computational design algorithms for approximating a given input geometry. The resulting designs can be rapidly manufactured via digital fabrication technologies such as laser cutting, CNC milling, or 3D printing. We validate our approach through a series of physical prototypes and present several application case studies, ranging from surgical implants to large-scale deployable architecture.

Star-shaped metrics for mechanical metamaterial design

“…Konaković et al [2016] and Malomo et al [2018] exploit parametric auxetic metamaterials to optimize two-dimensional plates that can assume three-dimensional custom shapes when deformed. In a similar vein, Konaković-Luković [2018] investigate the design of spatially-graded auxetic metamaterials that can be deployed into desired shapes. However, restricting materials for the inverse problems to originate from a single family of microstructures, selected a priori, limits the space of achievable behaviors and therefore the scope of the proposed methods.…”

Freeform quad-based kirigami

“…Follow-up work, likewise based on conformal geometry, treats the process of deployment of a more general class of cut/fold patterns. [Konaković-Luković et al 2018] construct structures that are fully deployed exactly when the limit of expansion is reached. The class of possible shapes achievable in this way includes nonconvex ones and is only restricted by the Fig.…”

Inverse Design Tool for Asymmetrical Self-Rising Surfaces with Color Texture

“…Researchers successfully fabricated 3D surfaces with inflatable structures [Skouras et al 2014], cut-and-sew method [Mori and Igarashi 2007], and non-stretchable airbags [Ou et al 2016]. Auxetic structures can transform under air pressure, gravity, or manual activation [Konaković-Luković et al 2018;Wang et al 2018a]. The in-plane strain of pneumatic channels can be turned into out-ofplane shape change [Siéfert et al 2019].…”