PSI - Issue 37

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

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Procedia Structural Integrity 37 (2022) 934–940

© 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 Pedro Miguel Guimaraes Pires Moreira © 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 Pedro Miguel Guimaraes Pires Mor ira Abstract The inherent viscoelasticity of the matrix phase, polymer composites are prone to creep and stress relaxation, making it a great challenge when they are used in long-term applications. Therefore, the main goal of the present study is to analyse the time-dependent behaviour of hybrid nanocomposites, and, for this purpose, experimental tests were carried out in compression, tensile and bending modes in which the load (for stress relaxation tests) and the displacement (for creep tests) were recorded during the loading time. It was possible to conclude, in terms of stress relaxation, that the bending mode had the lowest value, while the highest was observed for the tensile mode. In terms of creep behaviour, the tensile mode had the highest displacement while the bending and compression mode had similar values. © 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 Pedro Miguel Guimaraes Pires Moreira 1. Introduction More than design considerations, conventional manufacturing technologies are a real obstacle to the production of some structures. In this context, additive manufacturing (AM) is a recent technique capable of overcoming these limitations, in which they are produced layer by layer from a CAD file and without requiring multi-steps, labour intensive processes, high costs for moulds and long processing time. Fused filament fabrication (FFF) is the most widely process, and this technique is based on the extrusion of heated feedstock plastic filaments through a nozzle to deposit layers onto a platform to produce parts layer by layer directly from a computer-aided design model. However, one of the main limitations of this AM technique is related to the low mechanical properties of 3D printed parts (Love et al., 2014; Tekinalp et al., 2014; Torrado Perez et al. 2014). Therefore, the development of composite materials is seen as an easy way to improve the mechanical properties of components produced by FFF. In 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 Pedro Miguel Guimaraes Pires Moreira 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 Pedro Miguel Guimaraes Pires Moreira Abstract The inherent viscoelasticity of the matrix phase, polymer composites are prone to creep and stress relaxation, making it a great challenge when they are used in long-term applications. Therefore, the main goal of the present study is to analyse the time-dependent behaviour of hybrid nanocomposites, and, for this purpose, experimental tests were carried out in compression, tensile and bending modes in which the load (for stress relaxation tests) and the displacement (for creep tests) were recorded during the loading time. It was possible to conclude, in terms of stress relaxation, that the bending mode had the lowest value, while the highest was observed for the tensile mode. In terms of creep behaviour, the tensile mode had the highest displacement while the bending and compression mode had similar values. Keywords: Nanocomposites; Additive manufacturing (AM); Fused filament fabrication (FFF); Creep; Stress relaxation; Mechanical testing. Keywords: Nanocomposites; Additive manufacturing (AM); Fused filament fabrication (FFF); Creep; Stress relaxation; Mechanical testing. 1. Introduction More than design considerations, conventional manufacturing technologies are a real obstacle to the production of some structures. In this context, additive manufacturing (AM) is a recent technique capable of overcoming these limitations, in which they are produced layer by layer from a CAD file and without requiring multi-steps, labour intensive processes, high costs for moulds and long processing time. Fused filament fabrication (FFF) is the most widely process, and this technique is based on the extrusion of heated feedstock plastic filaments through a nozzle to deposit layers onto a platform to produce parts layer by layer directly from a computer-aided design model. However, one of the main limitations of this AM technique is related to the low mechanical properties of 3D printed parts (Love et al., 2014; Tekinalp et al., 2014; Torrado Perez et al. 2014). Therefore, the development of composite materials is seen as an easy way to improve the mechanical properties of components produced by FFF. In ICSI 2021 The 4th International Conference on Structural Integrity Creep and stress relaxation behaviour of 3D printed nanocomposites P.N.B. Reis a , S. Valvez b , J.A.M. Ferreira a ICSI 2021 The 4th International Conference on Structural Integrity Creep and stress relaxation behaviour of 3D printed nanocomposites P.N.B. Reis a , S. Valvez b , J.A.M. Ferreira a a Department of Mechanical Engineering, CEMMPRE, University of Coimbra, Coimbra, Portugal b C-MAST, Department of Electromechanical Engineering, University of Beira Interior, Covilhã, Portugal a Department of Mechanical Engineering, CEMMPRE, University of Coimbra, Coimbra, Portugal b C-MAST, Department of Electromechanical Engineering, University of Beira Interior, Covilhã, Portugal

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 Pedro Miguel Guimaraes Pires Moreira 10.1016/j.prostr.2022.02.028