Analysis of superimposed influence of double layer gas flow on gas-assisted extrusion of plastic micro-tube / T.-K. Liu in INTERNATIONAL POLYMER PROCESSING, Vol. XXXV, N° 2 (05/2020)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXV, N° 2 (05/2020) . - p. 158-168 Titre : Analysis of superimposed influence of double layer gas flow on gas-assisted extrusion of plastic micro-tube Type de document : texte imprimé Auteurs : T.-K. Liu, Auteur ; X.-Y. Huang, Auteur ; Z. Ren, Auteur ; C. Luo, Auteur ; J.-M. Tan, Auteur Année de publication : 2020 Article en page(s) : p. 158-168 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Eléments finis, Méthode des Matières plastiques -- Extrusion Microtubes Morphologie (matériaux) Simulation par ordinateur Index. décimale : 668.4 Plastiques, vinyles Résumé : A plastic micro-tube is extremely small, and the melt is still in a molten state when the melt exits the die. The inner layer gas still flows in the micro-cavity after leaving the die, therefore, the diameter of the micro-tube increases gradually. When the outer layer gas leaves the die, it blows directly to the outer wall of the micro-tube. The flow of the double layer gas has a great influence on the extrusion of the micro-tube. To this end, a double layer gas-assisted extrusion model based on gas/melt two-phase flow is established. It focuses on the overlay effect of the double layer gas flow on the forming micro-tube. Through a finite element numerical simulation of the micro-tube extrusion process, forming the double gas layer inside and outside the tube wall, respectively, we obtain the shape, velocity, pressure drop and first normal stress difference of the micro-tube. The analysis shows that the double gas layer inside and outside the tube wall have asymmetrical effect on the melt, and they must be analyzed at the same time; the first normal stress difference is generated at the entrance of the die, exit of the die and downstream of the die exit; it reflects the extrusion deformation of the gas to the micro-tube, the degree of extrusion on the micro-tube wall, the distribution of the velocities X and Y, and the distribution of the pressure drop, to some extent. Compared with the micro-tube gas-assisted extrusion experiment, when the gas pressure is large, the result is consistent with the phenomenon of irregular corrugation on the wall surface of the micro-tube, the wall at the exit of the die is rapidly thinned and the wall downstream of the die exit gradually thins. Note de contenu : - MATERIALS AND METHODS : Materials - Experimental experiments - NUMERICAL SIMULATION THEORIES AND METHODS : Geometric models and finite element models - Control equations and constitutive Boundary conditions - Numerical simulation parameters - Software and numerical methods - RESULTS AND DISCUSSION : Experimental results and analysis - SIMULATION RESULTS AND ANALYSIS : Micro-tube morphology analysis - Gasdensity field analysis - Velocity field analysis - Pressure field analysis - First normal stress difference (NI) analysis DOI : https://doi.org/10.3139/217.3891 En ligne : https://drive.google.com/file/d/1EIMUWeMg1ugIVWAU4xpYROLIajp1eLxP/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34010 [article]

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