Designing Shape Morphing Behavior through Local Programming of Mechanical Metamaterials

Abstract

Shape morphing implicates that a specific condition leads to a morphing reaction. The material thus transforms from one shape to another in a predefined manner. In this paper, not only the target shape but rather the evolution of the material's shape as a function of the applied strain is programmed. To rationalize the design process, concepts from informatics (processing functions, for example, Poisson's ratio (PR) as function of strain: ν = f(ε) and if‐then‐else conditions) will be introduced. Three types of shape morphing behavior will be presented: (1) achieving a target shape by linearly increasing the amplitude of the shape, (2) filling up a target shape in linear steps, and (3) shifting a bulge through the material to a target position. In the first case, the shape is controlled by a geometric gradient within the material. The filling kind of behavior was implemented by logical operations. Moreover, programming moving hillocks (3) requires to implement a sinusoidal function εy = sin (εx) and an if‐then‐else statement into the unit cells combined with a global stiffness gradient. The three cases will be used to show how the combination of mechanical mechanisms as well as the related parameter distribution enable a programmable shape morphing behavior in an inverse design process.

Piece‐By‐Piece Shape‐Morphing: Engineering Compatible Auxetic and Non‐Auxetic Lattices to Improve Soft Robot Performance in Confined Spaces

“…[30][31][32] Programmability is a unique feature of mechanical metamaterials, which is realized by adjusting local mechanical properties via tuning geometrical parameters. Previous studies used programmability of mechanical metamaterials to create stiffness gradient, [33] to control energy absorption characteristics [34] , and also to obtain shape-morphing characteristics by adjusting geometrical parameters in order [35][36][37] .…”

Single‐Step‐Lithography Micro‐Stepper Based on Frictional Contact and Chiral Metamaterial

“…[37] Auxetic metamaterials [30,38] are also widely used in the field of medical devices. [39] Self-guided shape-changing metamaterials [40][41][42][43][44] are expected to replace folding machinery and telescopic mechanisms, and bistable structures to replace traditional propellers and drive bionic fish. [45] Buckling-driven…”

Micro‐Scale Auxetic Hierarchical Mechanical Metamaterials for Shape Morphing

“…Shape morphing, [1][2][3][4][5][6][7][8] utilizing the topological or space-time properties [9][10][11] and the ability to control mechanical properties [12] of functional materials [13][14][15][16][17][18][19][20][21][22][23] remain some of the main challenges in materials science. At the same time, the possibility of constructing materials possessing such properties is in high demand as it may lead to the design of structures superior to currently known biomedical and other devices used in various industries.…”