PSI - Issue 42

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ Structural Integrity Procedia 00 (2019) 000 – 000 Structural Integrity Procedia 00 (2019) 000 – 000

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Procedia Structural Integrity 42 (2022) 680–686

© 2022 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 23 European Conference on Fracture – ECF23 The results show that all specimens with cell patterns absorb more strain energy than the solid specimen does. Although the solid specimen is the stiffest, both cell patterns (auxetic and honeycomb) have higher performance indices considering the important weight reduction. For around 35 % of reduction in the maximum measured load, the auxetic pattern at 0° can absorb up to 88% more energy compared to the solid specimen. This proves its capability of delaying the crack initiation and enhancing the fracture toughness. SENB specimens were designed with different cell patterns for fracture toughness assessment. (i) Auxetic pattern at 0° parallel to the notch direction, (ii) at 90° perpen icular to the notch direction and (iii) a conventional honeycomb tt r is defined with equivalent cell density on the specimen surf ce. T ree-point bending tests have been carried out to evaluate the fractur toughness of each spe imen. The mec anical performance ratio of specimens was evaluated by dividing the absorbed energy till fract re over the specimen weight. The ratios were also comp red to a solid specimen ratio taken as a reference in this study. The results show t at all specimens with cell patterns absorb mor strai energy than the solid sp cimen does. Although the solid specimen is the stiffest, both cell patterns (auxetic and h neyc mb) hav higher performance indices considering the important weight reduction. For around 35 % of reduction in the maximum measured load, the auxeti pattern at 0° can absorb up to 88% more energy c mpared t the solid specimen. This proves its capability of delaying the crack initiation and enhancing the fracture toughness. 23 European Conference on Fracture - ECF23 Improvement of fracture toughness based on auxetic patterns fabricated by metallic extrusion in 3D printing Marouene Zouaoui a,b , Omar Saifouni a,b *, Julien Gardan a,b , Ali Makke b , Naman Recho c , Julien Kauffmann b 23 European Conference on Fracture - ECF23 Improvement of fracture toughness based on auxetic patterns fabricated by metallic extrusion in 3D printing Marouene Zouaoui a,b , Omar Saifouni a,b *, Julien Gardan a,b , Ali Makke b , Naman Recho c , Julien Kauffmann b a Université de Technologie de Troyes, UR-LASMIS, 12 rue Marie Curie, Troyes 10000, France b EPF-School of engine ring, 2 Rue Fernand Sastre, Rosières-prés-Troyes 10430, France c Université Clermont Auverg e, Inst tut Pascal CNRS-UMR 6602, PB 10448, Clermont-Ferrand 63000, France Abstract This study aims to evaluate the effect of auxetic patterns on the fracture toughness of 3D printed metallic specimens manufactured by metallic extrusion of 17-4PH stainless steel. When it is pulled in the horizontal direction, the auxetic material expands in the vertical axis. This occurs since it has a negative Poisson’s ratio. In this work auxetic cell structures have been employed i n fractur mechanics characterization of Single Edge Notch Bending SENB specimens in order to improve their fracture toughness dynamically during str in. a Université de Technologie de Troyes, UR-LASMIS, 12 rue Marie Curie, Troyes 10000, France b EPF-School of engineering, 2 Rue Fernand Sastre, Rosières-prés-Troyes 10430, France c Université Clermont Auvergne, Institut Pascal CNRS-UMR 6602, PB 10448, Clermont-Ferrand 63000, France Abstract This study aims to evaluate the effect of auxetic patterns on the fracture toughness of 3D printed metallic specimens manufactured by metallic extrusion of 17-4PH stainless steel. When it is pulled in the horizontal direction, the auxetic material expands in the vertical axis. This occurs since it has a negative Poisson’s ratio. In this work auxetic cell structures have been employed i n fracture mechanics characterization of Single Edge Notch Bending SENB specimens in order to improve their fracture toughness dynamically during strain. SENB specimens were designed with different cell patterns for fracture toughness assessment. (i) Auxetic pattern at 0° parallel to the notch direction, (ii) at 90° perpendicular to the notch direction and (iii) a conventional honeycomb pattern is defined with equivalent cell density on the specimen surface. Three-point bending tests have been carried out to evaluate the fracture toughness of each specimen. The mechanical performance ratio of specimens was evaluated by dividing the absorbed energy till fracture over the specimen weight. The ratios were also compared to a solid specimen ratio taken as a reference in this study.

* Corresponding author. Tel.: +33 325 70 73 51; fax: +0-000-000-0000 . E-mail address: omar.saifouni@epf.fr * Corresponding author. Tel.: +33 325 70 73 51; fax: +0-000-000-0000 . E-mail ad ress: oma saifouni@epf.fr

2452-3216 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of 23 European Conference on Fracture - ECF23 2452-3216 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of 23 European Conference on Fracture - ECF23

2452-3216 © 2022 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 23 European Conference on Fracture – ECF23 10.1016/j.prostr.2022.12.086