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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An efficient analysis of resin transfer molding process using extended finite element method

Jung, Yeonhee 02 September 2013 (has links) (PDF)
Numerical simulation for Resin Transfer Molding (RTM) manufacturing process is attempted by using the eXtended Finite Element Method (XFEM) combined with the level set method. XFEM allows to obtaining a good numerical precision of the pressure near the resin flow front, where its gradient is discontinuous. The enriched shape functions of XFEM are derived by using the level set values so as to correctly describe the interpolation with the resin flow front. In addition, the level set method is used to transport the resin flow front at each time step during the mold filling. The level set values are calculated by an implicit characteristic Galerkin FEM. The multi-frontal solver of IPSAP is adopted to solve the system. This work is validated by comparing the obtained results with analytic solutions.Moreover, a localization method of XFEM and level set method is proposed to increase the computing efficiency. The computation domain is reduced to the small region near the resin flow front. Therefore, the total computing time is strongly reduced by it. The efficiency test is made with simple channel or radial flow models. Several application examples are analyzed to demonstrate ability of this method. A wind turbine blade is also treated as industrial application. Finally, a Graphic User Interface (GUI) tool is developed so as to make easy the pre/post-processing of the simulation.
2

An efficient analysis of resin transfer molding process using extended finite element method / Une analyse efficace du procédé RTM à l’aide de la méthode XFEM

Jung, Yeonhee 02 September 2013 (has links)
Le procédé de fabrication par RTM (Resin Transfer Molding) a été étudié numériquement à l’aide de la méthode XFEM (eXtended Finite Element Method) combinée avec la méthode Level set. La méthode XFEM permet d’obtenir une bonne précision numérique de la pression près du front d’écoulement, où son gradient est discontinu. Les fonctions de forme enrichies de la méthode XFEM sont proposées à l’aide des valeurs de Level set en vue de décrire correctement l’interpolation avec le front d’écoulement. En plus, la méthode de Level set est utilisée pour transporter le front d’écoulement à chaque pas de temps durant le remplissage du moule. Les valeurs de Level set sont calculées à l’aide d’une méthode de Galerkin implicite. Le solveur multi-frontal d’IPSAP a été utilisé pour la résolution du système. Cette étude a été validée en comparaison avec les solutions analytiques.En outre, une méthode de localisation avec XFEM et la méthode Level set a été proposée afin d’améliorer l’efficacité de calcul. Elle permet de réduire le domaine de calcul près du front d’écoulement. Par conséquent, le temps de calcul est fortement réduit grâce à cette méthode. Un test d’efficacité a été fait avec des modèles simples en écoulement laminaire ou radial.Quelques exemples d’application sont présentés pour illustrer la capacité de cette méthode. Une pale d’éolienne a également traitée comme application industrielle. Enfin, une interface d’utilisateur graphique a été développée en vue de fournir une facilité des pré- et post-processus. / Numerical simulation for Resin Transfer Molding (RTM) manufacturing process is attempted by using the eXtended Finite Element Method (XFEM) combined with the level set method. XFEM allows to obtaining a good numerical precision of the pressure near the resin flow front, where its gradient is discontinuous. The enriched shape functions of XFEM are derived by using the level set values so as to correctly describe the interpolation with the resin flow front. In addition, the level set method is used to transport the resin flow front at each time step during the mold filling. The level set values are calculated by an implicit characteristic Galerkin FEM. The multi-frontal solver of IPSAP is adopted to solve the system. This work is validated by comparing the obtained results with analytic solutions.Moreover, a localization method of XFEM and level set method is proposed to increase the computing efficiency. The computation domain is reduced to the small region near the resin flow front. Therefore, the total computing time is strongly reduced by it. The efficiency test is made with simple channel or radial flow models. Several application examples are analyzed to demonstrate ability of this method. A wind turbine blade is also treated as industrial application. Finally, a Graphic User Interface (GUI) tool is developed so as to make easy the pre/post-processing of the simulation.

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