Designing a light fabric metamaterial being highly macroscopically tough under directional extension: first experimental evidence

By Francesco dell'Isola, T. Lekszycki, Marek Pawlikowski, R. Grygoruk, L. Greco. 2015

201 citations recorded by the source corpus.

In this paper, we study a metamaterial constructed with an isotropic material organized following a geometric structure which we call pantographic lattice. This relatively complex fabric was studied using a continuous model (which we call pantographic sheet) by Rivlin and Pipkin and includes two families of flexible fibers connected by internal pivots which are, in the reference configuration, orthogonal. A rectangular specimen having one side three times longer than the other is cut at 45° with respect to the fibers in reference configuration, and it is subjected to large-deformation plane-extension bias tests imposing a relative displacement of shorter sides. The continuum model used, the presented numerical models and the extraordinary advancements of the technology of 3D printing allowed for the design of some first experiments, whose preliminary results are shown and seem to be rather promising. Experimental evidence shows three distinct deformation regimes. In the first regime, the equilibrium total deformation energy depends quadratically on the relative displacement of terminal specimen sides: Applied resultant force depends linearly on relative displacement. In the second regime, the applied force varies nonlinearly on relative displacement, but the behavior remains elastic. In the third regime, damage phenomena start to occur until total failure, but the exerted resultant force continues to be increasing and reaches a value up to several times larger than the maximum shown in the linear regime before failure actually occurs. Moreover, the total energy needed to reach structural failure is larger than the maximum stored elastic energy. Finally, the volume occupied by the material in the fabric is a small fraction of the total volume, so that the ratio weight/resistance to extension is very advantageous. The results seem to require a refinement of the used theoretical and numerical methods to transform the presented concept into a promising technological prototype.

Subfields: Civil and Structural Engineering, Control and Systems Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/666e349aa461fd40a5e3dd87a29fcc59f2f1c968

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Citations in the corpus

Linear pantographic sheets: Asymptotic micro-macro models identification (2017, methodology): “Recently the attention has been attracted by a particular class of microstructure: that which produces so called pantographic continua ([37, 36, 34, 35, 51, 66]).”
Pantographic metamaterials: an example of mathematically driven design and of its technological challenges (2018, methodology): “The shear strain introduced in this model is different from that defined in the Pipkin continuum model [10,34,35].”
Mechanical metamaterials associated with stiffness, rigidity and compressibility: a brief review (2017, background): “One challenge is how to deal with substantial geometric complexity when studying three-dimensional mechanical metamaterials, such as three-dimensional pentamode structures [44,285] or plane pantographic metamaterials [391].”
Synthesis of Fibrous Complex Structures: Designing Microstructure to Deliver Targeted Macroscale Response (2015, background): “This structure can have a very advantageous strength/weight ratio, and it is experimentally proved that it exhibits a particularly safe behavior in fracture [357], since it is capable of sustaining load in a stable fashion long after the inception of fracture: the part of energy absorbed by the syst”
Hencky-type discrete model for pantographic structures: numerical comparison with second gradient continuum models (2016, background): “The comparison with the previously obtained results found in [3,5] is really comforting: there is a total correspondence of the predictions.”
Large deformations of planar extensible beams and pantographic lattices: heuristic homogenization, experimental and numerical examples of equilibrium (2016, methodology): “The experimental setting is the same as the one described in [1], however, the measurements presented here are based on the acquisition and elaboration of a larger set of data.”