On induced properties and self heating during free blowing of PET preform / Y.-M. Luo in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 3 (07/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 3 (07/2019) . - p. 330-338 Titre : On induced properties and self heating during free blowing of PET preform Type de document : texte imprimé Auteurs : Y.-M. Luo, Auteur ; Luc Chevalier, Auteur Année de publication : 2019 Article en page(s) : p. 330-338 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Auto-échauffement (matériaux) Bouteilles en matières plastiques Matières plastiques -- Propriétés mécaniques Matières plastiques -- Soufflage Polyéthylène téréphtalate Préformes Objet constituant la majeur partie d’une pièce à fabriquer et qui nécessite un travail supplémentaire pour devenir une pièce finie. Ce terme s’utilise notamment pour le moulage, l’usinage, la taille d’outils en silex, la fabrication de fibre optique… Index. décimale : 668.4 Plastiques, vinyles Résumé : The great influence of temperature on polymer's behavior is well known and a 10°C increase can lead to a 10-time reduction of the viscosity near the glass transition temperature. To manage accurate simulation of thermoforming processes, and particularly the stretch blow molding process that is managed in the vicinity of Tg, it is necessary to take into account the self heating phenomena that may have impact on induced properties. In the particular case of polyethylene terephthalate (PET), injected preforms have been blown with different initial temperature and followed using a thermal camera. For an identical final volume of the blown preform, the influence of initial temperature on self-heating is discussed. Back to room temperature, induced mechanical properties are measured using digital image correlation: bottles are blown under different pressures and the strain fields are measured. Using the virtual field method on a region of interest of the bottle, these results allow the identification of the induced mechanical properties. Comparison between the self-heating and the induced modulus is managed and the effect of the self heating on the free blown shapes and induced properties is discussed. Note de contenu : - Experimental measurement : self heating - Identification of induced modulus : bottle under pressure - Influence of initial temperature on self heating and induced modulus under pressure DOI : https://doi.org/10.3139/217.3759 En ligne : https://drive.google.com/file/d/19aibzQK6Wui4xSah5uIQhnGpSDPd3XdW/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32895 [article]

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Simplified modeling of convection and radiation heat transfer during infrared heating of PET sheets and preforms / Y.-M. Luo in INTERNATIONAL POLYMER PROCESSING, Vol. XXX, N° 5 (11/2015)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXX, N° 5 (11/2015) . - p. 554-565 Titre : Simplified modeling of convection and radiation heat transfer during infrared heating of PET sheets and preforms Type de document : texte imprimé Auteurs : Y.-M. Luo, Auteur ; L. Chevalier, Auteur ; F. Utheza, Auteur ; X. Nicolas, Auteur Année de publication : 2015 Article en page(s) : p. 554-565 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Calcul Eléments finis, Méthode des Matières plastiques -- Moulage par injection-étirage-soufflage Polyéthylène téréphtalate Préformes Objet constituant la majeur partie d’une pièce à fabriquer et qui nécessite un travail supplémentaire pour devenir une pièce finie. Ce terme s’utilise notamment pour le moulage, l’usinage, la taille d’outils en silex, la fabrication de fibre optique… Rayonnement infrarouge Simulation par ordinateur Thermocinétique Index. décimale : 668.4 Plastiques, vinyles Résumé : Initial heating conditions and temperature effects have an important influence during the injection stretch blow molding process of PET preforms. The paper provides a simplified modeling of the infrared (IR) flux provided by the IR lamps and the convection heat transfer with air, for the finite element simulation of the heating of PET samples. This modeling enables fast thermal simulations in industrial context. First, a complete 2D simulation of the air convection around a PET sheet sample is conducted using ANSYS/FLUENT to compute the local convection heat transfer coefficient. The distribution of this coefficient along the PET wall is then interpolated by a best linear fit function of the wall position to provide the boundary condition of the convection heat transfer thereafter. This boundary condition, coupled with the calculation of the infrared flux absorbed by the PET sheet sample, allows a 3D calculation of the time evolution of the sample temperature. This calculation is validated by comparing the experimental temperature distribution of the PET sheet obtained from an IR camera with the numerical results of the simulation. Second, we focus on the modeling of the heating of a cylindrical PET preforms by IR lamps. In our approach, the IR heating flux is calculated using the spectral and surface-to-surface radiation laws adapted to the sample geometry. The air convection effect around the preform is modeled using the heat transfer coefficient identified from the 2D plane sheet case. It is applied on the boundaries of a simpler model in Comsol where only the preform is meshed. The temperature distribution on the outer surface of the preform is compared to experimental measurements by thermal imaging. A good agreement is observed which validates the whole approach used. Note de contenu : - IDENTIFICATION OF THE THERMAL BOUNDARY CONDITIONS FOR THE INFRARED HEATING SIMULATION OF A PET SHEET : Complete 2D model of IR heating and natural air convection - Computation of convective heat transfer coefficient - Validation of a h for a 3D simulation of the PET sheet alone - MODELLING OF THE INFRARED HEATING OF THE PET PREFORM : Computation of the incident radiation on the PET preform - 3D simulation of the IR heating of a PET preform and experimental comparaison DOI : 10.3139/217.3092 En ligne : https://drive.google.com/file/d/1jNPbTXwC48CDbEjTkf9wyiMahsJcX2b5/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=24818 [article]

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Strain field measurement on 3D surfaces : application to petaloid base of PET bottles under pressure / L. Chevalier in INTERNATIONAL POLYMER PROCESSING, Vol. XXV, N° 2 (05/2010)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXV, N° 2 (05/2010) . - p. 93-108 Titre : Strain field measurement on 3D surfaces : application to petaloid base of PET bottles under pressure Type de document : texte imprimé Auteurs : L. Chevalier, Auteur ; Y.-M. Luo, Auteur ; E. Monteiro, Auteur ; B. Plantamura, Auteur Année de publication : 2010 Article en page(s) : p. 93-108 Note générale : Appendices - Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Validation of stretched blown bottles of polyethylene terephthalate (PET) by using numerical simulation is an important industrial goal. This necessitates the identification of the PET material characteristics. Because the biaxial elongation of macromolecules induces great modifications of the mechanical properties of the material, it is difficult to manage an accurate simulation: properties are not well known in the base or neck region of the bottles. The aim of the work presented here is to provide an identification tool for the orthotropic elastic properties in the 3D regions of PET bottles of carbonated soft drinks. More specifically, we focus on the behavior of the petaloid bases when bottles are submitted to internal pressure like during burst or ESC (environmental stress cracking) tests. A stereo correlation tool has been developed in order to build digital 3D surface; comparing the initial surface with the same surface when the bottle is under pressure, it is possible to evaluate the membrane strains at each point of the petaloid surface. Two bases, one with large valleys (LV) between the five feet and one with small valleys (SV) which highlight very different behavior at the ESC test, are compared with this tool. Coupled with a finite element simulation managed on the same bases, these results allow the identification of the induced mechanical properties. The LV case presents specific characteristics that are discussed in the last section of the paper. Note de contenu : 1. Introduction : Modeling the stretch blow molding 2. Experimental measurements : Environmental stress cracking (ESC test - Surface construction by stereo correlation - Thickness measurements. 3. Theoretical basics of the identification method : Strain field calculation - Numerical - Experimental comparison. 4. Results and discussion : Elastic properties distribution in petaloid base - Correlation between ESC ans strain field. DOI : 10.3139/217.2327 En ligne : https://drive.google.com/file/d/1B3BV2uRNVQ1oQD08Aq6i82_xPY9UK0ZJ/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=9323 [article]

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