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Numerical Simulation of the Fibre-Motion during the Extrusion of Short-Fibre-Reinforced Glass-MeltsFibre-reinforced materials are characterized by an anisotropic behaviour of the mechanical properties. which is caused by the alignment of the embedded fibres. In the case of short-fibrecompounds this behaviour is strongly influenced by the mechanism of flow during the manufacturing process. Numerical simulation methods are prcfercntially used to get informations about the orientation of the reinforced fibres at the end of the moldingprocess and to improve the properties of the compound.For that, a model is developed, which calculates the motion of the short-fibres in the area of flow. basing on a three-dimensional finite-element-computation. Thereby the interaction between the particular fibres during the orientation process is considered by using an interaction coefficicnt.Examplificd at the extrusion of short fibre reinforced glassmelts, the fibre orientation is determined at models with different geometries of the pressing tool and variable boundary conditions. This procedure allows to determine the influence of the processparameters on the expected quality of the composite. The represented simulation-model can also be used for other molding-and extrusion-processes of fibre reinforced materials.

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Mit Hilfe des StrangpreRverfahrens lassen sich durch die Einlagerung von pliittchenfiirmigen Teilchen aus hochfesten und hochmoduligen Werkstoffen in die xu verpressende Glasschmelze Verbundstlbe mit iin Vergleich min unverstlrkten Glas erhiihtem Elastizitatsmodul und gesteigerter Festigkeit erzeugen. Diese Verbesserung der niechanischen Eigenschaften ruhrt in erster Linie von der Ausrichtung der Plattchen her, die durch die laminare Scherstromung der hochviskosen Glasschmelze in der Uinformzone und im Matrizenkanal bewirkt wird. Uni statistische Aussagen uber die Plattchenorientierung innerhalb des extrudierten Verbundstranges zu erhalten, werden neben experimentellen auch bevorzugt theoretische Untersuchungsmethoden angewandt. Durch die systematische Variation der einzelnen StrangpreBparameter laBt sich auf diese Weise eine zielgerichtete Optimierung des Herstellungsprozesses bezuglich der Verstiirkungswirkung der eingelagerten Partikel erzielen.Zu diesem Zweck wild ein Modell vorgestellt. welches ausgehend von einem init Hilfe der Methode der Finiten Elemente berechneten Geschwincligkeitsprofil der Extrusionsstromung die Bewegung der Pliittchen wBhrend des Umformvorganges simuliert. Die gegenseitige Beeinflussung der VerstBrkungskomponenten wird dabei durch die Einfuhrung eines Interaktionskoeffizienten berucksichtigt. Im einzelnen wird das Ausrichtungsverhalten der Einlagerungspartikel an Modellen mit unterschiedlichen Randbedingungen in Abhangigkeit der Geometrie und des Volumenanteils der Verst~lrkungskomponenten untersucht. Die daraus gewonnenen theoretischen Ergebnisse werden anschliefiend den an extrudierten Verbundsttiben mit Hilfe der automatischen Bildanalyse ermittelten experi mentelle n Werten gegenubergestel It. Dieser Vergleich belegt die Eignung des vorgestellten Simulationsmodells.By embedding platelets consisting of materials with high modulus of elasticity and strength in the extruded gl sites with increased Young's modulus and strength compared to non-reinforced glass can be produced. This improvement of the mechanical properties is prirnarily caused by the orientation of the platelets, which is a result of the laminar shear-flow of the highly viscous glass-melt within the deformation zone and within the die channel. To acquire statistical statements about the plateletorientation within the extruded compound rods theoretical research methods are preferentially employed over experimental ones. By the systematic variation of individual extrusion-parameters a systematic optimization of the manufacturing process concerning the reinforcing effect of the embedded particles is made possible.To this end a model has been developed, which simulates the motion of the platelets during the deformation process based on a finite-element computed velocity profile development of the extrusion flow. The interaction between the reinforcing particles is considered by using an interaction coefficient. In detail the onentation-behaviour of the embedded particles is analyzed as a function of their geometry and volu...

Elasticity and mechanical damping of an unidirectional SiC-short-fibre reinforced alkali-lime-silicate-glassThe embedment of short-fibres in inorganic glasses enables as is well known a considerable improvement of the strength as well as the fracturc toughness of these materials. Still not investigated is the influence of the fibre-reinforcement on the mechanical damping of the composites.In this paper the dynamic mechanical thermal analysis is presented, which was used to determine mechanical damping and elasticity of not reinforced and unidirectional SiC-short-fibre reinforced AR-glass as a function of temperature and fibre volume fraction. The results show that the composite specimens exhibitbesides a glass-typical temperature dependence of the dampingan additional damping part, which can be attributed to the fibre reinforcement.This damping part is just as the specimen elasticity to a large extent dependent on the fibre volume fraction and is mainly associated with sliding processes in the fibre-matrixinterface under the vibrating stress. Specimens with a fibre volume fraction of 10% and a temperature of 15°C show -in comparison to non-reinforced AR-glass -an about 100% increased damping value connected with a nearly 50% decreased Young's modulus.