Free boundary viscous flows at micro and mesolevel during liquid composites moulding process

Abstract

SUMMARYNumerical simulation aspects, related to low Reynolds number free boundary viscous ows at micro and mesolevel during the resin impregnation stage of the liquid composite moulding process (LCM), are presented in this article. A free boundary program (FBP), developed by the authors, is used to track the movement of the resin front accurately by accounting for the surface tension e ects at the boundary. Issues related to the global and local mass conservation (GMC and LMC) are identiÿed and discussed. Unsuitable conditions for LMC and consequently GMC are uncovered at low capillary numbers, and hence a strategy for the numerical simulation of such ows is suggested.FBP encompasses a set of subroutines that are linked to modules in ANSYS. FBP can capture the void formation dynamics based on the analysis developed. We present resin impregnation dynamics in two dimensions. Extension to three dimensions is a subject for further research. Several examples are shown and e ciency of di erent stabilization techniques are compared.

Post-processing Techniques Suitability for Mesolevel Free Boundary Flows

“…Numerical techniques to address the movement of the flow were already developed in the Free Boundary Program (FBP) [2][3][4]. Numerical simulations can track the advancement of the resin front promoted by both hydrodynamic pressure gradient and capillary action.…”

Mass Conservation Enhancement of Free Boundary Mesolevel Flows during LCM Processes of Composites Manufacturing

“…Because of the explicit integration along the time scale, such errors are irreversible. Several stabilization techniques were implemented in FBP to eliminate this effect [2,7,14]. In this article we will present more appropriate techniques for stabilization, based on the weak formulation of the problem.…”

“…In the case of flow across the fibre tows, experimental evidence shown in [3][4][5] and numerical results presented in [6][7] clearly demonstrate that filling of the fibre tows is delayed. Resin advance, although helped by strong intra-tow capillary pressure, must overcome a fibre arrangement with much lower intra-tow permeability; thus there could hardly exist some scenario, which would move the front more or less uniformly.…”

“…Numerical simulations can track the advancement of the resin front promoted by both hydrodynamic pressure gradient and capillary action [2,7,[12][13][14]. Quasi steady state assumption can be exploited in the full flow domain and explicit time integration is adopted along the time scale.…”

Post-processing Techniques in Free Boundary Flows during Liquid Composite Moulding Processes

“…Numerical techniques to address the movement of the flow were already developed in the Free Boundary Program (FBP) [2][3][4]. Simulations can track the advancement of the resin front promoted by both, hydrodynamic pressure gradient and capillary action.…”