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Numerical Method to Predict Void Formation during The Liquid Composite Molding Process
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Resumo(s)
Void formation during the injection phase of the liquid composite molding process
can be explained as a consequence of the non-uniformity of the flow front progression. This is
due to the dual porosity within the fiber perform (spacing between the fiber tows is much larger
than between the fibers within in a tow) and therefore the best explanation can be provided by a
mesolevel analysis, where the characteristic dimension is given by the fiber tow diameter of the
order of millimeters. In mesolevel analysis, liquid impregnation along two different scales; inside
fiber tows and within the open spaces between the fiber tows must be considered and the
coupling between the flow regimes must be addressed. In such cases, it is extremely important to
account correctly for the surface tension effects, which can be modeled as capillary pressure
applied at the flow front. Numerical implementation of such boundary conditions leads to illposing
of the problem, in terms of the weak classical as well as stabilized formulation. As a
consequence, there is an error in mass conservation accumulated especially along the free flow
front. A numerical procedure was formulated and is implemented in an existing Free Boundary
Program to reduce this error significantly.
Descrição
Palavras-chave
void formation, surface tension, capillary pressure, mass conservation, free boundary flow, mesolevel analysis, dual porosity