SILVA , Luisa

The first works devoted to the evolution of elongated particles are mainly due to Jeffery, which exhibits the evolution equation for orientation. In a simple shear flow and Newtonian fluid, the particle was found to undergo a periodic revolution, called the Jeffery orbit centered around the vorticity axis. This orbit is controlled by an aspect...

Contents: Introduction. Observations. Models. Computation of fibre orientation in injection moulding. Conclusions. References

Micro-injection molding is frequently used in micro-medical, micro-optic and micro-mechanics due to its effectiveness for mass production. This work focuses mainly on offering numerical tools to model the injection of textured molds. Such tools can predict the different filling scenarios of the micro-details and consequently offer optimal...

The chapter focuses on fibre reinforced thermoplastics or polymer composites which are mainly produced by injection and compression molding using particles having mostly cylindrical shape (short or long fibers made up of glass, carbon or flax). The aim of this fibre addition is to improve the mechanical properties of final parts. However these...

This chapter is dedicated to the simulation of composite forming processes. It concerns numerical methods for molding, at the different material scales, involving multiphysics analysis. From the different possible numerical techniques, we focus on a stabilized finite element method for the resolution of the continuum equations (mass, momentum...

TA Mixed Finite Element (MFE) method for 3D non-steady flow of a viscoelastic compressible fluid is presented. It was used to compute polymer injection flows in a complex mold cavity, which involves moving free surfaces. The flow equations were derived from the Navier-Stokes incompressible equations, and we extended a mixed finite element...

Micro-injection moulding is frequently used for the fabrication of devices in many different fields such as micro-medical technologies, micro-optics and micro-mechanics thanks to its effectiveness for mass production. This work focuses mainly on offering numerical methodology to model the injection into textured moulds. Such approach can...

La perméabilité d'un renfort tissé, utilisé dans les procédés LCM, est un paramètre significatif pour modéliser leur imprégnation. La tension de surface est un paramètre influant au cours de l'imprégnation. Une approche monolithique pour la résolution numérique d'écoulements multiphasiques est proposée et appliquée aux écoulements à l'échelle...

Mesh adaptation has proven to be very efficient for simulating transient multiphase computational fluid dynamics applications. In this work, we present a new parallel anisotropic mesh adaptation technique relying on an edge based error estimator. It provides a high level of accuracy while substantially reducing the computational effort. This...

Ce travail propose une approche multi-domaine pour modéliser l'écoulement d'un fluide complexe (un fluide de Bingham). Une attention plus particulière est portée à l'interface liquide-air et à l'orientation des fibres. Les applications concernent l'ajout de tiges de métal au béton liquide afin d'améliorer les propriétés mécaniques des...

An efficient method to compute permeability of fibrous media is presented. An immersed domain approach is used to represent the porous material at its microscopic scale and the flow motion is computed with a stabilized mixed finite element method. Therefore the Stokes equation is solved on the whole domain (including solid part) using a penalty...

Micro-injection moulding is frequently used for the mass production of devices in micro-medical technologies, micro-optics and micro-mechanics. This work focuses mainly on offering numerical tools to model the injection of micro-textured moulds. Such tools can predict the different filling scenarios of the micro-details and consequently offer...

Dans un fluide Newtonien, l'orientation d'une fibre est parfaitement décrire par l'équation de Jeffery. Dans cette étude,on utilise un rhéomètre numérique pour étudier l'évolution d'une fibre dans un champ de cisaillement simple pour des fluidesviscoélastiques Oldroyd-B. Pour les fluides viscoélastiques, la période de rotation augmente avec le...

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A precise procedure to generate complex 2D and 3D statistical virtual microstructures in a finite element (FE) context is described. This technique, based on Laguerre tessellations and advancing front method, level-set description of interfaces and anisotropic meshing adaptation, is detailed for equiaxial polycrystal and powder RVEs defined by...

We present a finite element approach assisted with anisotropic mesh adaptation to model fibre-reinforced composites on compression molding processes. A single mesh embeds all the important phases (Die tool + composite material + Punching tool), implicitly described by level-set functions. A viscous transverse isotropic model for molding...

A transverse isotropic viscous model accounting for the anisotropy exhibited in fiber-reinforced composites is integrated in the numerical platform of the software Rem3D®. Simulations under various mechanical loadings are tested for volume fiber concentrations of 3.5% and 14.7%. Equivalent stresses and equivalent strain rate deformations given...

A transverse isotropic viscous model accounting for the anisotropy exhibited in fiber-reinforced composite is integrated in the numerical platform of the software Rem3D®. Simulations under various mechanical loading are tested for volume fiber concentrations of 3.5% and 14.7%. Equivalent stresses and equivalent strain rate deformations given by...

The polymer coextrusion process is a new method of sheet metal lining. It allows to substitute lacquers for steel protection in food packaging industry. The coextrusion process may exhibit flow instabilities at the interface between the two polymer layers. The objective of this study is to check the influence of processing and rheology...

La fabrication d'un film multicouche peut être réalisée de manière économique par l'utilisation de la technique de coextrusion. Des instabilités peuvent apparaître à l'interface entre les deux polymères ce qui rend le produit inexploitable. L'objectif de cette étude est d'étudier numériquement l'influence du procédé et des paramètres...