An emerging class of hyperbolic lattice exhibiting tunable elastic properties and impact absorption through chiral twisting

Applied Physics Letters

et al. 2021

Mechanical metamaterials are advanced engineering materials that exhibit unusual properties that cannot be found in nature. The elastic properties (i.e., elastic modulus and Poisson's ratio) of mechanical metamaterials can be tuned by changing the geometry of their fundamental unit cells. This allows for the design of metamaterial lattices with targeted quasi-static properties. However, it is not clear how these freedoms contribute to the dynamic properties of mechanical metamaterials. We, therefore, used experimental modal analysis, numerical simulations, and analytical models to study the dynamic response of meta-structures with different values of the Poisson's ratio. We show that Poisson's ratio strongly affects the damping properties of the considered mechanical metamaterials. In particular, we found an inverse relationship between the damping ratio and the absolute value of the Poisson's ratio of the meta-structures. Our results suggest that architected meta-structures similar to those studied could be tailor-made to improve the dissipative performance of mechanical systems. Geometrical design could play an important role in this regard by providing the possibility to tune the various types of quasi-static and dynamic properties of such mechanical metamaterials.

Section: =3mentioning

confidence: 99%

Dynamic characterization of 3D printed mechanical metamaterials with tunable elastic properties

Zadeh

Alijani

Applied Physics Letters

et al. 2021

“…Origami structures made of thin sheet material offer a promising remedy to the above two challenges [6][7][8][9][10]. Thanks to conceptual simplicity and the absence of complicated assembly, origami structures have been widely and innovatively applied in practical engineering, including metamaterials [11][12][13], energy absorption/buffering structures [14][15][16], robots [17][18][19], architectures [20][21][22], robot grippers [23][24][25], and to name only a few. The origami structure's coexisting structural properties of flexibility and rigidity provide it with an inherent superiority when applied to flexible robot grippers [26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear topology optimization design and gripping tests of a novel origami chomper-based flexible gripper

Liu

Wen

et al. 2023

Preprint

Although the flexible origami gripper can handle a wide range of objects, there is a need for significant further improvement in its gripping performance. This study develops a novel nonlinear topology optimization (NTO) method to enhance the gripping performance of an origami chomper-based flexible gripper. The proposed NTO method incorporates the additive hyperelasticity technique and multi-resolution design (MRD) strategy with the advantages of being computationally efficient, having excellent convergence, and enabling refined design. The effectiveness of the proposed NTO method is validated by two compliant mechanism benchmark examples, i.e., the displacement inverter and gripper mechanisms. We apply the NTO method to the origami chomper-based flexible gripper to redistribute the material at the creases to obtain the optimized origami chomper-based flexible gripper. Several optimized origami chomper-based flexible gripper prototypes are fabricated by using laser cutter, followed by a series of experiments to test the gripping performances, including gripping range capability under an identical input load, maximum gripping ratio, gripping adaptability, and achieving richer gripping characteristics by size scaling. Results demonstrate that the optimized origami chomper-based flexible gripper can handle a wide range of objects irregularities in textures and uneven shapes;and the gripping range capability can be significantly enhanced by the NTO method. We also show that the optimized origami chomper-based flexible gripper can enable effective gripping of objects across scales from millimeters to centimeters to decimeters through size scaling.

“…Mechanical metamaterials are unique structures whose properties are determined not by their material composition as conventional structures but by the geometric configuration of the microstructure units [1][2][3]. Due to its unconventional mechanical properties, for instance, negative Poisson's ratio, negative effective mass, negative modulus, chirality, et al, it has broad application prospects [4][5][6][7][8]. The empirical method is the mainstream method of designing such mechanical metamaterials.…”

Section: Introductionmentioning

confidence: 99%

Stacked-origami mechanical metamaterial with tailored multistage stiffness

Wen

Long

et al. 2021

Preprint

Origami-baed metamaterial has shown remarkable mechanical properties rarely found in natural materials, but achieving tailored multistage stiffness is still a challenge. This study proposes a novel zigzag-base stacked-origami (ZBSO) metamaterial with tailored multistage stiffness property based on crease customization and stacking strategies. A high precision finite element (FE) model to identify the stiffness characteristics of the ZBSO metamaterial has been established, and its accuracy is validated by quasi-static compression experiments. Using the verified FE model, we demonstrate that the multistage stiffness of the ZBSO metamaterial can be effectively tailored through two manners, i.e. varying the microstructures (through introducing new creases to the classical Miura origami unit cell) and altering the stacking way. Three strategies are utilized to vary the microstructure, i.e. adding new creases to the right, left, or both sides of the unit cell. We further reveal that the proposed ZBSO metamaterial has several outstanding advantages compared with traditional mechanical metamaterials, e.g. material independent, scale-invariant, lightweight, and excellent energy absorption capacity. The unravelled superior mechanical properties of the ZBSO metamaterials pave the way for the design of the next-generation cellular metamaterials with tailored stiffness properties.