Modeling of Heat Transfer and Unsaturated Flow in Woven Fiber Reinforcements during Direct Injection-Pultrusion Process of Thermoplastic Composites

International audienceThis paper provides a methodology for the modeling of heat transfer and polymer flow during direct thermoplastic injection pultrusion process. Pultrusion was initially developed with thermosets which have low viscosity. But the impregnation becomes a critical point with thermoplastics which exhibit higher viscosity. There are very few reported works on direct thermoplastic impregnation with injection within the die. In addition, the rare studies have not adequately addressed the issue of unsaturated flow in woven fiber reinforcements. The solution proposed here, models the polymer flow through dual-scale porous media. A heat transfer model is coupled to a flow model enriched with a sink term. Specific changes of variables are made so as to model the steady state solution of unsaturation along a continuous process. The sink term, added to the continuity equation, represents the absorption rate of polymer by the bundles. Data were measured on a pultrusion line and micrographs confirmed the modeling strategy with an unsaturated flow approach. The flow modeling coupled to heat transfer of the thermoplastic pultrusion process aims at determining the saturation evolution through the die so as to manufacture pultruded profiles with the lowest residual porosity

Ein neues Markenzeichen der Universität : Das Zentrum für Medien und Interaktivität (ZMI)

Das Zentrum für Medien und Interaktivität (ZMI) der Justus-Liebig-Universität Gießen ist eine in dieser Form neuartige Einrichtung, die anwendungsorientierte und praxisnahe Grundlagenforschung zu medienbezogenen Fragestellungen betreibt. Vor gut drei Jahren trafen sich Lehrende der Gießener Universität aus verschiedenen Fachbereichen, die in der einen oder anderen Form mit kommunikations- und medienwissenschaftlichen Fragen befasst sind. Aus dem universitären Alltag heraus entstand die Idee, diese Aktivitäten zu bündeln, und die Leitung der Justus-Liebig-Universität hat diese Initiative gerne aufgegriffen und sich zu eigen gemacht. Nach knapp zweijährigem Planungsvorlauf wurde das ZMI am 1. April 2001 gegründet. Es bündelt medienbezogene und mediengestützte Lehrangebote und bietet Dienstleistungen und Beratung im Bereich Online-Medien an. Partner des ZMI sind universitäre und außeruniversitäre Forschungs- und Bildungseinrichtungen, politische und administrative Institutionen, Medien- und andere Unternehmen

Measurements of Droplet Deformation in Simple Shear Flow with Zero Interfacial Tension

The deformation of Newtonian droplets with zero interfacial tension in a Newtonian matrix is studied in simple shear flow for viscosity ratios ranging from 0.095 to 10.29. The experiments use a counterrotating Couette apparatus driven by independent servo motors, with a control scheme that keeps the droplet centered under a video camera. Droplet deformation is measured by analyzing the video images, using the method of moments. Both the matrix and the droplet are silicone oils, and the droplet contains a fluorescent dye. Low-viscosity droplets stretch monotonically, while higher viscosity droplets may stretch, wobble, or tumble. The theory of Wetzel and Tucker (2000) for ellipsoidal droplets with zero interfacial tension is compared to the data, by adjusting those portions of the initial shape and orientation that are not observable in the experiment. The agreement is excellent in all cases, requiring only that the initial droplet shape be close to an ellipsoid

A global methodology to measure continuously mechanical properties in compression and permeability of fiber reinforcements

International audienc

Mechanical properties and permeability measurements of fibre reinforcements: A continuous method

International audienc

Modeling, monitoring and control of composite structures processing

International audienc

Mechanical properties and permeability measurements of fibre reinforcements: A continuous method

International audienc

Mechanical properties and permeability measurements of fibre reinforcements: A continuous method

International audienc

Models for shear properties/behavior of dry fibrous materials at various scales: a review

International audienceDuring forming operations of dry fibrous materials in order to get the composite preforms, the deformation mode is substantially determined by the occurring shear strains. Consideration of the material shear response namely from the theoretical point of view has gained high importance because multi-scale nature and anisotropy of fibrous materials complicates their experimental investigation , which raises the question of the tests realizability, complexity, and cost. This work analyses and classifies the existing theoretical approaches for the shear prediction with respect to the mathematical principles employed, as well as with respect to the architecture of diverse fibrous materials, to which the approach can be applied. Both classifications depend in turn on the main criterion of classification emphasized here – the scale of observation of the shear load. According to the theoretical framework, the approaches form the main groups based either on purely geometrical reasoning, or on finite elements analysis, or on energy minimization, or on forces equilibrium principle. The approaches are compared according to the total of mechanical factors included in their analysis and typical for a certain stage of shear load and a certain scale (micro-, meso-, or macro-). The advantages and difficulties of each of the methods are evaluated