3D-printed highly stretchable curvy sandwich metamaterials with superior fracture resistance and energy absorption

Hamzehei, R, Bodaghi, M ORCID: https://orcid.org/0000-0002-0707-944X and Wu, N, 2024. 3D-printed highly stretchable curvy sandwich metamaterials with superior fracture resistance and energy absorption. International Journal of Solids and Structures, 286-28: 112570. ISSN 0020-7683

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Abstract

This paper focuses on the potential of curvy mechanical metamaterials to show how topological design can significantly enhance fracture toughness along the in-plane and out-of-plane (through-depth) directions. The conventional re-entrant unit cell is first reformulated by introducing local curvy ligaments and then additively manufactured by three-dimensional (3D) printing to form a center/edge-notch lattice metamaterial. The new conceptual design provides multi-stiffness unit cells, helping to control stress distribution within a structure under tensile load, specifically in the vicinity of the notches where stress concentrations occur. In other words, curvy unit cells are capable of arresting and blunting the notch under tensile loads and toughening the metamaterials. The crack tip opening displacement (CTOD) method calculates the fracture toughness. Not only can the fracture of lattice metamaterials be controlled along the in-plane direction by replacing unit cells in the sensitive parts of the metamaterials, but a new assembly method is also proposed. This offers that different thin plates of metamaterials with different layouts can be sandwiched to control out-of-plane fracture propagation (through-depth propagation of opening mode fracture) for the first time in fracture mechanics. This novel sandwiching method offers a multi-step fracture and significantly improves the fracture behavior of the lattice metamaterials from brittle to ductile by taking advantage of multiple through-thickness thin plates instead of considering one thick specimen. A detailed analysis of the effects of the ligament curvature value on the fracture behavior is presented. The results reveal that the more curvature, the more extension (ductility) will be realized, but too large curvature design can provide lower energy absorption capacity.

Item Type:	Journal article
Publication Title:	International Journal of Solids and Structures
Creators:	Hamzehei, R., Bodaghi, M. and Wu, N.
Publisher:	Elsevier BV
Date:	January 2024
Volume:	286-28
ISSN:	0020-7683
Identifiers:	Number Type 10.1016/j.ijsolstr.2023.112570 DOI 1843196 Other
Rights:	© 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Divisions:	Schools > School of Science and Technology
Record created by:	Laura Ward
Date Added:	08 Dec 2023 14:55
Last Modified:	08 Dec 2023 14:55
URI:	https://irep.ntu.ac.uk/id/eprint/50501

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