Bistable Auxetic Mechanical Metamaterials Inspired by Ancient Geometric Motifs

By Ahmad Rafsanjani, Damiano Pasini. 2016

436 citations recorded by the source corpus.

Abstract Auxetic materials become thicker rather than thinner when stretched, exhibiting an unusual negative Poisson’s ratio well suited for designing shape transforming metamaterials. Current auxetic designs, however, are often monostable and cannot maintain the transformed shape upon load removal. Here, inspired by ancient geometric motifs arranged in square and triangular grids, we introduce a class of switchable architected materials exhibiting simultaneous auxeticity and structural bistability. The material concept is experimentally realized by perforating various cut motifs into a sheet of rubber, thus creating a network of rotating units connected with compliant hinges. The metamaterial performance is assessed through mechanical testing and accurately predicted by a coherent set of finite element simulations. A discussion on a rich set of mechanical phenomena follows to shed light on the main design principles governing bistable auxetics.

Subfields: Civil and Structural Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/5190a646b75ed1d5bb6e2ecebf0aa9dbe9217622

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Citations in the corpus

Exploiting Microstructural Instabilities in Solids and Structures: From Metamaterials to Structural Transitions (2017, background): “14(a)) and 2D arrays of rotating units [190] result in large extension and a range of nonlinear mechanical responses.”
Auxetic metamaterials and structures: a review (2018, methodology): “A typical model: (a) ancient geometric motif; (b) a bistable auxetic mechanical metamaterial before deformation; (c) a bistable auxetic mechanical metamaterial after deformation [89].”
Mechanics of Metamaterials with Negative Parameters (2020, background): “A family of stress, Poisson’s ratio, and strain energy density curves for both the square and triangular unit cells plotted against strain is furnished by Rafsanjani and Pasini (2016b) in Fig.”
Auxetic mechanical metamaterials: from soft to stiff (2023, background): “[39], negative stiffness [40], negative wet properties [41], extraordinary bending Poisson’s effect [42], and strain ratedependent Poisson’s ratio [43].”