Abstract
Certain types of patterned metamaterials - gridshells and honeycombs - are capable of bistable behaviour through a tailored combination of local and global geometric parameters. This is an alternative to prestressed or composite materials, which are typically used to induce multistability in thin structures. Globally bistable structures, contrary to arrays of bistable elements, allow large deformations in a single step. Furthermore, this category of structures offers greater manufacturability and scalability compared to laminate, prestressed or multimaterial shells, since only geometry has to be considered. The simplicity of the material and geometrical requirements afford the designer easy and direct embedding in larger functional structures. In this study, the local and global response of bistable gridshells is interrogated through a manageable strain energy model, as well as through numerical and experimental methods. In addition, construction of bistable gridshells by employing various additive methods is examined and prototypes are presented for a series of functional devices. Finally, the availability of printed parts much larger than the build plate using commercial 3D printers is demonstrated, effectively ``expanding'' the dimensions of the build plate.
Highlights
Architectured materials with prescribed mechanical properties are increasingly being explored for their potential to influence diverse applications in actuation, acoustics and sensing to name a few
Two distinct areas of inquiry, namely architectured materials and additive manufacturing, are maturing in parallel and their combined capabilities open up new opportunities for designers and manufacturers alike
These opportunities were examined for one category of morphing structures, known as multistable gridshells, accelerating the convergence of the underlying technologies
Summary
Architectured materials with prescribed mechanical properties are increasingly being explored for their potential to influence diverse applications in actuation, acoustics and sensing to name a few One category of such tunable metamaterials, namely multistable structures, offers new capabilities in energy harvesting (Harne and Wang, 2013), impact absorption (Whitman and La Saponara, 2007), and medical implants (Bobbert et al, 2018). Many examples of 3D-printed, multistable structures are available in the literature (Shan et al, 2015; Che et al, 2017; Chen and Shea, 2018) These tend to fall into one of the following categories: structures based on bistable unit cells, most commonly a snap-through beam mechanism; structures employing exotic materials, such as shape memory polymers; and, multimaterial systems, which remain prohibitively expensive for the majority of users. A collection of demonstrators of functional components is presented and explained
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