PSI - Issue 33

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Procedia Structural Integrity 33 (2021) 1103–1114

© 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the IGF ExCo © 2021 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review Statement: Peer-review under responsibility of the scientific committee of the IGF ExCo Keywords: Bio-inspired composites; Nacre-like microstructure; Finite deformations; Instability; Microscopic instabilities; Loss of ellipticity. Abstract This work deals with the onset of instabilities at the microscopic and macroscopic scales in uniaxially compressed bioinspired composite materials with periodic microstructure. particular, the interchange between macro- and micro-instabilities in incompressible nacre-like composite materials has been investigated for different combinations of platelets aspect ratio, platelets volume fraction and shear modulus contrast between platelets and soft matrix. It has been demonstrated that the critical stretch ratios and the critical mode shapes are highly influenced by both the geometrical and materials parameters. The stability analyses highlighted that the microscopic stability analysis provides in most cases strong underestimates of the critical stretch ratios (adopting a small unit cell assembly), and that, by performing a macroscopic stability analysis based on the strong ellipticity condition of the homogenized tangent moduli tensor, a more accurate evaluation of the load associated with the primary instability can be instead obtained with less computational efforts. In addition, for a wide range of the investigated parameters, the instabilities are found to be characterized by long wavelengths with an in-phase critical mode shape. © 2021 The Authors. Pu lished by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review Statement: Peer-review under responsibility of the scientific committee of the IGF ExCo Keywords: Bio-inspired composites; Nacre-like microstructure; Finite deformations; Instability; Microscopic instabilities; Loss of ellipticity. I F26 - 26th International Conference on Fracture and Structural Integrity tability analysis at the icro- and acro-scales in periodic bioinspired composites ndrea Pranno 1 , Fabrizio reco 1* , ai ondo Luciano 2 , Lorenzo Leonetti 1 , Umberto e aio 1 1 Department of Civil Engineering, University of Calabria, Via P. Bucci Cubo 39B, Rende 87036, Italy 2 Department of Engineering, Parthenope University of Naples, Naples, Italy. Abstract This work deals with th onset f inst bilitie at th microscopic and macroscopic scales in uniaxi lly com r ssed bioinspir d c mposite materials with periodic microstructure. p rticular, the interchange betw en acro- and micro-instabi ities in incompressible na re-like com o ite materials has be n investigated for different combinations of platelets aspect ratio, pl telets volume fraction and shear m dulus contrast between platelets and soft matrix. It has been demonstrated that the critical stretch r ti s a d the critical mode shapes are highly influenc d by both the geometrical and materials param ters. T stability analyses highlighted t at the microscopic stability analy is provides in most cases str ng underestimates of the critical stretch ratios (adopti g a small unit cell assembly), and that, by performing a macroscopic stability a alysis based on the strong ellipticity condition of the omogenized tangent moduli ten or, a more accurate evaluati n of the load associated with the primary instability can be instead obtained with less computational efforts. In addition, for a wide range of the investigated parameters, the instabilities are found to be characterized by long wavelengths with an in-phase critical mode shape. © 2021 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review Statement: Peer-review under responsibility of the scientific committee of the IGF ExCo Keywords: Bio-inspired composites; Nacre-like microstructure; Finite deformations; Instability; Microscopic instabilities; Loss of ellipticity. IGF26 - 26th International Conference on Fracture and Structural Integrity Stability analysis at the micro- and macro-scales in periodic bioinspired composites Andrea Pranno 1 , Fabrizio Greco 1* , Raimondo Luciano 2 , Lorenzo Leonetti 1 , Umberto De Maio 1 1 Department of Civil Engineering, University of Calabria, Via P. Bucci Cubo 39B, Rende 87036, Italy 2 Department of Engineering, Parthenope University of Naples, Naples, Italy. Abstract This work deals with the onset of instabilities at the microscopic and macroscopic scales in uniaxially compressed bioinspired composite materials with periodic microstructure. particular, the interchange between macro- and micro-instabilities in incompressible nacre-like composite materials has been investigated for different combinations of platelets aspect ratio, platelets volume fraction and shear modulus contrast between platelets and soft matrix. It has been demonstrated that the critical stretch ratios and the critical mode shapes are highly influenced by both the geometrical and materials parameters. The stability analyses highlighted that the microscopic stability analysis provides in most cases strong underestimates of the critical stretch ratios (adopting a small unit cell assembly), and that, by performing a macroscopic stability analysis based on the strong ellipticity condition of the homogenized tangent moduli tensor, a more accurate evaluation of the load associated with the primary instability can be instead obtained with less computational efforts. In addition, for a wide range of the investigated parameters, the instabilities are found to be characterized by long wavelengths with an in-phase critical mode shape. IGF26 - 26th International Conference on Fracture and Structural Integrity Stability analysis at the micro- and macro-scales in periodic bioinspired composites Andrea Pranno 1 , Fabrizio Greco 1* , Raimondo Luciano 2 , Lorenzo Leonetti 1 , Umberto De Maio 1 1 Department of Civil Engineering, University of Calabria, Via P. Bucci Cubo 39B, Rende 87036, Italy 2 Department of Engineering, Parthenope University of Naples, Naples, Italy.

* Corresponding author. Tel.: +390984496916. E-mail address: fabrizio.greco@unical.it * Corresponding author. Tel.: +390984496916. E-mail address: fabrizio.greco@unical.it * Corresponding author. Tel.: +390984496916. E-mail address: fabrizio.greco@unical.it

2452-3216 © 2021 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review Statement: Peer-review under responsibility of the scientific committee of the IGF ExCo 2452-3216 © 2021 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review Statement: Peer-review under responsibility of the scientific committee of the IGF ExCo 2452-3216 © 2021 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review Statement: Peer-review under responsibility of the scientific committee of the IGF ExCo

2452-3216 © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the IGF ExCo 10.1016/j.prostr.2021.10.123