Accurate Vacuum Assisted Resin Infusion simulation through a fluid-solid coupled modeling

The need for an increase of production rate in aerospace industry implies a growing interest in composite manufacturing process simulation with a strong requirement on predictive accuracy. In this context, ESI enhanced its PAM-COMPOSITES software introducing fluid-solid coupled approach in PAM-RTM module in order to simulate more accurately Vacuum Assisted Resin Infusion (VARI) process. VARI consists in impregnating a dry preform laid on a rigid mold and placed under a distribution medium and a vacuum bag. During the impregnation resin flows preferentially into the distribution medium and then in the preform which may undergo deformations due to the flexibility of the vacuum bag. Usual 2.5D approaches, using shell elements with thickness depending on resin pressure, cannot account for resin flow through the thickness due to permeability and fiber fraction gradients implied by the material used and/or solid mechanics effects (such as compression in curvatures). ESI new approach, resulting from several years of collaboration with academics, consists in a 3D finite element modeling. It is based on the coupling of resin flow, governed by Darcy’s law, with the preform behavior, considered as porous medium undergoing deformations, through Terzaghi’s principle. Thus it results in more predictive filling time and properties (thicknesses, fiber volume contents, geometry) of the final product