Cargando…

Idealized 3D Auxetic Mechanical Metamaterial: An Analytical, Numerical, and Experimental Study

Mechanical metamaterials are man-made rationally-designed structures that present unprecedented mechanical properties not found in nature. One of the most well-known mechanical metamaterials is auxetics, which demonstrates negative Poisson’s ratio (NPR) behavior that is very beneficial in several in...

Descripción completa

Detalles Bibliográficos
Autores principales: Ghavidelnia, Naeim, Bodaghi, Mahdi, Hedayati, Reza
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923447/
https://www.ncbi.nlm.nih.gov/pubmed/33672483
http://dx.doi.org/10.3390/ma14040993
_version_ 1783658904772673536
author Ghavidelnia, Naeim
Bodaghi, Mahdi
Hedayati, Reza
author_facet Ghavidelnia, Naeim
Bodaghi, Mahdi
Hedayati, Reza
author_sort Ghavidelnia, Naeim
collection PubMed
description Mechanical metamaterials are man-made rationally-designed structures that present unprecedented mechanical properties not found in nature. One of the most well-known mechanical metamaterials is auxetics, which demonstrates negative Poisson’s ratio (NPR) behavior that is very beneficial in several industrial applications. In this study, a specific type of auxetic metamaterial structure namely idealized 3D re-entrant structure is studied analytically, numerically, and experimentally. The noted structure is constructed of three types of struts—one loaded purely axially and two loaded simultaneously flexurally and axially, which are inclined and are spatially defined by angles [Formula: see text] and [Formula: see text]. Analytical relationships for elastic modulus, yield stress, and Poisson’s ratio of the 3D re-entrant unit cell are derived based on two well-known beam theories namely Euler–Bernoulli and Timoshenko. Moreover, two finite element approaches one based on beam elements and one based on volumetric elements are implemented. Furthermore, several specimens are additively manufactured (3D printed) and tested under compression. The analytical results had good agreement with the experimental results on the one hand and the volumetric finite element model results on the other hand. Moreover, the effect of various geometrical parameters on the mechanical properties of the structure was studied, and the results demonstrated that angle [Formula: see text] (related to tension-dominated struts) has the highest influence on the sign of Poisson’s ratio and its extent, while angle [Formula: see text] (related to compression-dominated struts) has the lowest influence on the Poisson’s ratio. Nevertheless, the compression-dominated struts (defined by angle [Formula: see text]) provide strength and stiffness for the structure. The results also demonstrated that the structure could have zero Poisson’s ratio for a specific range of [Formula: see text] and [Formula: see text] angles. Finally, a lightened 3D re-entrant structure is introduced, and its results are compared to those of the idealized 3D re-entrant structure.
format Online
Article
Text
id pubmed-7923447
institution National Center for Biotechnology Information
language English
publishDate 2021
publisher MDPI
record_format MEDLINE/PubMed
spelling pubmed-79234472021-03-03 Idealized 3D Auxetic Mechanical Metamaterial: An Analytical, Numerical, and Experimental Study Ghavidelnia, Naeim Bodaghi, Mahdi Hedayati, Reza Materials (Basel) Article Mechanical metamaterials are man-made rationally-designed structures that present unprecedented mechanical properties not found in nature. One of the most well-known mechanical metamaterials is auxetics, which demonstrates negative Poisson’s ratio (NPR) behavior that is very beneficial in several industrial applications. In this study, a specific type of auxetic metamaterial structure namely idealized 3D re-entrant structure is studied analytically, numerically, and experimentally. The noted structure is constructed of three types of struts—one loaded purely axially and two loaded simultaneously flexurally and axially, which are inclined and are spatially defined by angles [Formula: see text] and [Formula: see text]. Analytical relationships for elastic modulus, yield stress, and Poisson’s ratio of the 3D re-entrant unit cell are derived based on two well-known beam theories namely Euler–Bernoulli and Timoshenko. Moreover, two finite element approaches one based on beam elements and one based on volumetric elements are implemented. Furthermore, several specimens are additively manufactured (3D printed) and tested under compression. The analytical results had good agreement with the experimental results on the one hand and the volumetric finite element model results on the other hand. Moreover, the effect of various geometrical parameters on the mechanical properties of the structure was studied, and the results demonstrated that angle [Formula: see text] (related to tension-dominated struts) has the highest influence on the sign of Poisson’s ratio and its extent, while angle [Formula: see text] (related to compression-dominated struts) has the lowest influence on the Poisson’s ratio. Nevertheless, the compression-dominated struts (defined by angle [Formula: see text]) provide strength and stiffness for the structure. The results also demonstrated that the structure could have zero Poisson’s ratio for a specific range of [Formula: see text] and [Formula: see text] angles. Finally, a lightened 3D re-entrant structure is introduced, and its results are compared to those of the idealized 3D re-entrant structure. MDPI 2021-02-20 /pmc/articles/PMC7923447/ /pubmed/33672483 http://dx.doi.org/10.3390/ma14040993 Text en © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Ghavidelnia, Naeim
Bodaghi, Mahdi
Hedayati, Reza
Idealized 3D Auxetic Mechanical Metamaterial: An Analytical, Numerical, and Experimental Study
title Idealized 3D Auxetic Mechanical Metamaterial: An Analytical, Numerical, and Experimental Study
title_full Idealized 3D Auxetic Mechanical Metamaterial: An Analytical, Numerical, and Experimental Study
title_fullStr Idealized 3D Auxetic Mechanical Metamaterial: An Analytical, Numerical, and Experimental Study
title_full_unstemmed Idealized 3D Auxetic Mechanical Metamaterial: An Analytical, Numerical, and Experimental Study
title_short Idealized 3D Auxetic Mechanical Metamaterial: An Analytical, Numerical, and Experimental Study
title_sort idealized 3d auxetic mechanical metamaterial: an analytical, numerical, and experimental study
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923447/
https://www.ncbi.nlm.nih.gov/pubmed/33672483
http://dx.doi.org/10.3390/ma14040993
work_keys_str_mv AT ghavidelnianaeim idealized3dauxeticmechanicalmetamaterialananalyticalnumericalandexperimentalstudy
AT bodaghimahdi idealized3dauxeticmechanicalmetamaterialananalyticalnumericalandexperimentalstudy
AT hedayatireza idealized3dauxeticmechanicalmetamaterialananalyticalnumericalandexperimentalstudy