A two-phase flow model to simulate mold filling and saturation in Resin Transfer Molding

The final publication is available at Springer via http://dx.doi.org/10.1007/s12289-015-1225-zThis paper addresses the numerical simulation of void formation and transport during mold filling in Resin Transfer Molding (RTM). The saturation equation, based on a two-phase flow model resin/air, is coupled with Darcy s law and mass conservation to simulate the unsaturated filling flow that takes place in a RTM mold when resin is injected through the fiber bed. These equations lead to a system composed of an advection diffusion equation for saturation including capillary effects and an elliptic equation for pressure taking into account the effect of air residual saturation. The model introduces the relative permeability as a function of resin saturation. When capillary effects are omitted, the hyperbolic nature of the saturation equation and its strong coupling with Darcy equation through relative permeability represent a challenging numerical issue. The combination of the constitutive physical laws relating permeability to saturation with the coupled system of the pressure and saturation equations allows predicting the saturation profiles. The model was validated by comparison with experimental data obtained for a fiberglass reinforcement injected in a RTM mold at constant flow rate. The saturation measured as a function of time during the resin impregnation of the fiber bed compared very well with numerical predictions.The authors acknowledge financial support of the Spanish Government (Projects DPI2010-20333 and DPI2013-44903-R-AR), of the National Science and Research Council of Canada (NSERC) and of the Canada Reseach Chair (CRC) program.Gascón Martínez, ML.; García Manrique, JA.; Lebel, F.; Ruiz, E.; Trochu, F. (2016). A two-phase flow model to simulate mold filling and saturation in Resin Transfer Molding. 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On the variability of permeability induced by reinforcement distortions and dual scale flow in liquid composite moulding: A review

© 2019 A comprehensive review of experimental and analytical studies since 1990 on the variability of permeability induced by fibrous media (reinforcement) distortions across the composite part manufacturing chain is presented. The review covers variability in as-supplied dry reinforcements, which include tow waviness, tow size and tow shape variations, interconnectedness of the pore space inside the tows (tortuosity), and changes during production, handling or storage, affected by the reinforcement deformation (non-uniform shearing, stretching and compression) and nesting of the layers in the laminate. The review clearly indicates that the interdependencies among these parameters is one of the root causes of the spatial variation of the permeability of the preform. This has spurred recent work to quantify flow front and filling time variabilities and development of optimal injection strategies using stochastic flow simulations. State-of-the-art experimental and theoretical approaches and modelling of this stochastic behaviour within numerical frameworks for the design of composite manufacturing processes are introduced and future outlook on the role of such variability at different scales is forecasted.status: publishe