Gilles Dusserre

Mold Filling Simulation of Resin Transfer Molding Combining BEM and Level Set Method

Liquid Composite Molding (LCM) is a popular manufacturing process used in many industries. In Resin Transfer Molding (RTM), the liquid resin flows through the fibrous preform placed in a mold. Numerical simulation of the filling stage is a useful tool in mold design. In this paper the implemented method is based on coupling a Boundary Element Method (BEM) with a Level Set tracking. The present contribution is a two-dimensional approach, decoupled from kinetics, thermal analysis and reinforcement deformation occurring during the flow. Applications are presented and tested, including a flow close to industrial conditions.

Effect of Moisture on the Behaviour of an Extruded Clay Paste

In the industrial process, the moisture of the clay sheet obtained by extrusion and pressed to form a tile varies in time. It depends on the nature and the mixing of the raw materials during the production. In order to model and undersand the influence of the moisture on the pressing step, it is necessary to determine the parameters of the rheological and tribological laws. A study of the rheological behaviour, based on free compression tests on cylinder samples, allowed to use an elasto-visco-plastic behaviour for the extruded clay paste. The different constitutive parameters were estimated by an inverse analysis based on the experimental force/displacement curves. The identification was performed with the optimisation algorithm implemented in the commercial software Forge® 2009. The influence of the water content in the paste on the rheological parameters was identified and fitted using linear models. The friction factor was measured from tests on a rectilign tribometer. To understand the influence of the moisture, we simulated a compression test, using Forge® involving the shaping of a tile lug. This geometry is representative of the state of stress during the pressing of the tile, in an area currently sujected to defects. The numerical model show that an increase of eighteen percent of the moisture allows to decrease by half the pressing force.

Numerical simulations of clay tiles compression

During the pressing step, the clay tiles undergo stresses which result in the appearance of defects. A rheological study, based on free compression tests, allowed to confirm the Elasto-visco-plastic behaviour of the clay. The different constitutive parameters were estimated by fitting the force-displacement experimental curves using the optimisation algorithm (ES Metamodel) implanted in the commercial software Forge 2009®. The influence of the tribological parameters was studied using squeezing numerical simulations of a full tile. The numerical model was validated with experimental squeezing test of technological specimen with a tile lug. Then, we have compared experimental force with the numerical one and deduced that the clay/tool interface is not perfectly sliding. A friction Tresca’s law was used to model the clay/tool interface. Numerical results showed that the actual geometry of tile lug didn’t allow to form correctly the tile. Several areas undergo tensile stress, air traps ,... A new geometry of tile lug was proposed in order to limit this phenomenon. Using a simplified defect criteria (Latham and Cockroft), the numerical model allowed to locate the areas where there is a risk of crack.