Micro-residual stress measurement in nanocomposite reinforced polymers / H. R. Ziaei Moghadam in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 3 (07/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 3 (07/2019) . - p. 356-366 Titre : Micro-residual stress measurement in nanocomposite reinforced polymers Type de document : texte imprimé Auteurs : H. R. Ziaei Moghadam, Auteur ; S. A. Faghidian, Auteur ; Majid Jamal-Omidi, Auteur ; S. Rahmati, Auteur Année de publication : 2019 Article en page(s) : p. 356-366 Langues : Anglais (eng) Catégories : Composites à fibres de carbone Contraintes résiduelles Eléments finis, Méthode des Epoxydes Fraisage Matériaux hybrides Nanotubes de carbone à parois multiples Un nanotube de carbone multifeuillet est constitué de plusieurs feuillets de graphènes enroulés les uns autour des autres. Il existe deux modèles pour décrire la structure des nanotubes multifeuillets : - le modèle poupée russe: les plans de graphène sont arrangés en cylindres concentriques ; - le modèle parchemin: un seul feuillet de graphène est enroulé sur lui-même, comme une feuille de papier. Stratifiés -- Propriétés mécaniques Index. décimale : 668.4 Plastiques, vinyles Résumé : In the present study, residual stress is measured in fiber-reinforced SWCNT/epoxy at weight fractions of 0.1% and 0.5% with a cross-ply layup on a micro-scale. The mechanical properties of the SWCNT/epoxy composites were determined by tensile testing and the Young's modulus of the epoxy increased moderately with the addition of CNTs. The micro-residual stress of the cross-ply CF/epoxy and CNF-reinforced CF/epoxy laminates were measured using a new experimental approach. The micro-hole was milled by laser beam and the surface displacement was recorded by SEM after milling. In order to determine the residual stress from the recorded strain, the calibration matrix was calculated using the finite element method. The residual stress was obtained at a certain hole depth of specimens. The reliability of this approach was assessed by comparing the residual stress measurements from this method and from the standard hole-drilling method. The experimental results of the present approach confirmed that laser hole drilling SEM-DIC has excellent potential as a reliable method for measuring residual stress in polymer nanocomposites. Generally, CNT agglomerates, especially in high weight fractions, increased the micro-residual stress. An analytical method based on classical theory was used to calculate the residual stress and was compared with the experimental results. Good agreement was found between the results of the analytical methods and the experimental measurement. Note de contenu : - EXPERIMENTAL PROCEDURE - RESIDUAL STRESS MEASUREMENT : Laser SEM-DIC method - Obtaining full field strains - FINITE ELEMENT MODELING - ANALYTICAL ANALYSIS DOI : https://doi.org/10.3139/217.3756 En ligne : https://www.degruyter.com/document/doi/10.3139/217.3756/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32897 [article]

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A molecular dynamics study on the mechanical properties of defective CNT/epoxy nanocomposites using static and dynamic deformation approaches / Sina Afsharhashemkhani in INTERNATIONAL POLYMER PROCESSING, Vol. 37, N° 2 (2022)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 37, N° 2 (2022) . - p. 176-190 Titre : A molecular dynamics study on the mechanical properties of defective CNT/epoxy nanocomposites using static and dynamic deformation approaches Type de document : texte imprimé Auteurs : Sina Afsharhashemkhani, Auteur ; Majid Jamal-Omidi, Auteur ; Majid Tavakolian, Auteur Année de publication : 2022 Article en page(s) : p. 176-190 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites à fibres -- Défauts Composites à fibres de carbone -- Propriétés mécaniques Déformations (mécanique) Dynamique moléculaire Epoxydes Matériaux hybrides Simulation par ordinateur Index. décimale : 668.4 Plastiques, vinyles Résumé : In this paper, the mechanical behavior of epoxy polymer nanocomposite with continuous single-walled carbon nanotubes (SWCNT) with and without vacancy defects has been investigated based on two approaches of deformation, molecular mechanics (static) and molecular dynamics. In this regard, molecular simulation has been performed on the basis of the compass force field. In order to validate the research steps, the results obtained for pure epoxy polymer were compared with similar molecular dynamic simulations, which confirmed the simulation process. The research process proposed a method for controlling the symmetry of the system during equilibration with an asymmetric barostat. The Souza-Martins barostat was also used to apply loading and deformation control over a constant strain rate range. The results showed that in both deformation approaches (with and without calculating the contribution of kinetic energy), the presence of defects improved the transverse tensile and shear moduli, while the longitudinal tensile modulus decreased. Also, the improvement and decrease of the longitudinal tensile modulus and longitudinal shear modulus of the nanocomposite in comparison with the net polymer have been observed in both approaches, respectively. As a general result, it was observed that the contribution of kinetic energy has a major effect on the mechanical properties of pristine and defective nanocomposites. Note de contenu : - MD SIMULATION : Modeling of pristine and defective CNTs - Modeling of epoxy nanocomposites - Deformation simulation - Simulation details - RESULTS AND DISCUSSION : Mechanical properties of net polymer and nanocomposite - Static deformation approach - The role of deformation approach and defects - Table 1 : The specifications of the simulated cells after equilibration - Table 2 : Mechanical properties of CNT/epoxy nanocomposite with and without defects in nanotube by static strain-constant method - Table 3 : Mechanical properties of CNT/epoxy nanocomposite with and without defects in nanotube by dynamic method DOI : https://doi.org/10.1515/ipp-2021-4182 En ligne : https://drive.google.com/file/d/1B_mT1VPE2UItGd2CJGSHATIL5NngCjeo/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37623 [article]

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Numerical simulation of tensile residual stresses in SWCNT-reinforced polymer composites / M. R. Soleimany in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 1 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 1 (2021) . - p. 13-25 Titre : Numerical simulation of tensile residual stresses in SWCNT-reinforced polymer composites Type de document : texte imprimé Auteurs : M. R. Soleimany, Auteur ; Majid Jamal-Omidi, Auteur ; S. M. Nabavi, Auteur ; Majid Tavakolian, Auteur Année de publication : 2021 Article en page(s) : p. 13-25 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites à fibres de carbone -- Propriétés mécaniques Contraintes résiduelles Polyéthylène Polymères -- Propriétés mécaniques Simulation par ordinateur Traction (mécanique) Index. décimale : 668.4 Plastiques, vinyles Résumé : The residual stresses play a significant role in the mechanical properties and strengthening capability of nanocomposites. The present research aims to numerically investigate the residual stress relaxation in nanotube-reinforced polymers in response to mechanical tensile loading. The systems under study consist of the armchair and zigzag single-walled carbon nanotubes (SWCNT) embedded in a polymer matrix. The nanotubes and polymer matrix are assumed to be bonded by van der Waals interactions based on the Lennard-Jones (L-J) potential at the interface. The interactions between carbon atoms in the nanotube and nodes in the polymer matrix are modelled by equivalent springs. In order to evaluate the analysis of elastic-perfectly plastic using finite element (FE) modelling, first, relaxation of the plastic residual stresses on steel hemisphere in contact with a rigid flat surface was examined in a loading-unloading cycle and verified with available data. Afterwards, the residual stress relaxation in nanotubes with different space-frame structures was computed due to displacement-controlled loading. Finally, the stress state and the plastic residual stresses in the nanocomposite for different carbon nanotube content were analyzed and discussed during loading and unloading. Regarding the effect of tensile stress, it was revealed that nanotube structures have significant effects on the residual stresses created in the nanocomposite. Note de contenu : - Material properties of SWCNTs - Validation of simulation pProcess - Numerical simulation of residual stress in SWCNT - Residual stress analysis in a SWCNT-reinforced polymer nanocomposite - Table 1 : Tensile properties of CNTs (Wernik and Meguid, 2010) - Table 2 : Material properties used in the Jackson et al. (2005) study - Table 3 : Comparison of residual stress obtained from numerical estimation and available result - Table 4 : Mechanical properties of polyethylene - Table 5 : The maximum von-Mises stress and residual stress value for various armchair SWCNT structures - Table 6 : The maximum von-Mises stress and residual stress value for various zigzag SWCNT structures - Table 7 : The maximum von-Mises stress and residual stress value for SWCNT-reinforced polymer composites with various armchair structures DOI : https://doi.org/10.1515/ipp-2020-3957 En ligne : https://drive.google.com/file/d/1TiikaZ9_I7HOYQfjEA7JEe169IA9I7Z8/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36342 [article]

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