A 3D extension of pantographic geometries to obtain metamaterial with semi-auxetic properties

Stilz, Maximilian; Plappert, David; Gutmann, Florian; Hiermaier, Stefan

doi:10.1177/10812865211033322

Cited by 19 publications

(5 citation statements)

References 43 publications

(52 reference statements)

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“…53 Future research could also explore more complex pantographic unit cells featuring bi-pantographic motifs 54 or those that exhibit semi-auxetic or monoclastic deformations. [55][56][57] In this context, recent advancements in process speed, 58,59 approaches to enhance precision and fidelity in 2PP, 34 materials, 25,37,44 and novel laser sources 60,61 are expected to improve the feasibility of fabricating real-world applications or providing cost-effective rapid prototyping using 2PP in the near future.…”

Section: Discussionmentioning

confidence: 99%

Complex mechanical properties of 3D micro-metric pantographic metamaterials fabricated by two-photon polymerization

Barchiesi,

Mavrikos,

Giorgio

et al. 2024

Preprint

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Mechanical metamaterials consist of specially engineered features designed to tailor and enhance the mechanical properties of their constituent materials. In this context, 2D pantographic fabrics have gained attention for their unique deformation behavior, providing remarkable resilience and damage tolerance. This study explores micro-metric metamaterials with 3D pantographic motifs, aiming to transfer these properties to small scales. 3D micro-metric structures were designed using 2D pantographic fabrics arranged in multiple layers, each featuring unit cells with quasi-perfect pivots. Relatively large specimens of 3D micro-metric pantographs, measuring 158μm x 250 μm x 450 μm, were fabricated using two-photon polymerization in various configurations. These specimens were mechanically characterized through in-situ scanning electron microscopy microindentation under conditions of cyclic deformation. Structural failures were subsequently assessed via helium-ion microscopy. The 3D micro-metric pantographs exhibited complex mechanical properties, some aligning with those of 2D pantographic fabrics, while new properties, such as a dissipative response and softening, were identified. Nonetheless, the 3D micro-metric pantographs demonstrated great resilience against deformation and enhanced resistance to undesired out-of-plane motions, indicating their potential for novel applications in advanced engineering fields. Additionally, the findings can potentially lead to optimizing and enriching theoretical models describing the mechanical behavior of pantographic metamaterials.

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Section: Discussionmentioning

confidence: 99%

Complex mechanical properties of 3D micro-metric pantographic metamaterials fabricated by two-photon polymerization

Barchiesi,

Mavrikos,

Giorgio

et al. 2024

Preprint

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“…If perfect pivot joints are introduced, deformation modes that do not change the internal elastic energy, so-called floppy or zero energy modes, appear [23–25]. Pantographic ortho-blocks show a strong semi-auxetic behavior [12, 13]. Unusual deformed shapes were also found for simulations of cylindrical pantographic shells where pantographic sheets described as second-gradient continua have been initially bent to the shape of a cylinder [26, 27].…”

Section: Introductionmentioning

confidence: 99%

“…By adding additional parallel pantographic sheets, which are all interconnected by pivots, pantographic blocks are formed, and a periodicity is added to the third dimension [9][10][11]. For pantographic ortho-blocks, the additional parallel sheets are interconnected by orthogonal pantographics sheets instead of pivots [12,13]. Besides a high compliance compared to their base materials, they typically need to be described with higher-order continuum theories [14][15][16][17][18][19] when viewed as continua to properly predict their deformed shapes [5,[20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Chirality effects in panto-cylindrical structures

Stilz,

Breuling,

Eugster

et al. 2024

Mathematics and Mechanics of Solids

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In this paper, we apply a numerical integration strategy recently developed for determining the deformation shapes of structures constituted by Cosserat rods, to predict the behavior of panto-cylinders. Panto-cylinders have, as microstructure, a set of two families of helicoidal beams interconnected by perfect or elastic joints. The pivot’s free rotation axis is, in the reference configuration, orthogonal to the cylindrical surfaces spanned by the beams. We perform a series of numerical simulations looking for the mechanical parameters which exalt the chirality effects in the structure. For the performed compression, extensions, shear, and torsion tests, we find chiral deformation patterns with a dependence on the type of joint and its length.

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“…Another kinds of generalization of pantographic structures for 2.5D and 3D lattices has been considered recently in Refs. 39,40 . We can also mention the recent work 41 , where the similar chiral geometry of the unit cells with asymmetrically placed struts were proposed.…”

Section: Introductionmentioning

confidence: 99%

Improved mechanical performance of quasi-cubic lattice metamaterials with asymmetric joints

Solyaev

Ustenko

Babaytsev

et al. 2023

Preprint

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In this paper, we propose a simple method for the modification of the unit cells in the lattice metamaterials that provides an improvement of their impact strength. The idea is based on the introduction of small mutual offsets of the interconnected struts inside the unit cells. In such way, the joints between the struts become asymmetric and the overall geometry of the unit cells can be defined as the quasi-cubic with the axis of chirality. Considering four types of cubic lattices with BCC, BCT, FCC and octahedron structures, we modified their geometry and investigated the influence of the offsets and the unit cell size on the overall performance in static and dynamic tests. From the experiments we found that the small offsets (less than the strut diameter) can allow to increase the impact strength of 3d-printed polymeric specimens in 1.5-3 times remaining almost the same density and static mechanical properties. Based on the numerical simulations, we show that the explanation of the observed phenomena can be related to the increase of plastic deformations and damage accumulation in the unit-cells with asymmetric joints leading to the transition from the quasi-brittle to the ductile type of fracture in tested specimens.

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A 3D extension of pantographic geometries to obtain metamaterial with semi-auxetic properties

Cited by 19 publications

References 43 publications

Complex mechanical properties of 3D micro-metric pantographic metamaterials fabricated by two-photon polymerization

Complex mechanical properties of 3D micro-metric pantographic metamaterials fabricated by two-photon polymerization

Chirality effects in panto-cylindrical structures

Improved mechanical performance of quasi-cubic lattice metamaterials with asymmetric joints

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