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Vacuum-assisted resin transfer molding (VARTM) is a very suitable solution for composite manufacturing industry. It allows the manufacturing of large and complex shape parts at low costs. However, the simulation of this process is complicated due to myriad physical phenomena involved, specifically the strong coupling between the resin flow and the preform compressibility, i.e. hydro-mechanical coupling. Moreover, the use of the distribution medium involves two types of flow: Planar flow and through-the-thickness flow. These flows cannot be considered together by a 2D model. On the other hand, 3D models require an important amount of computation time. This article presents a VARTM modeling approach that takes into account the hydro-mechanical coupling and the coexistence of planar and transverse flows. The proposed modeling approach allows the simulation of the infusion process in the case of multilayer preform with different materials and orientations, including the distribution medium. This model is validated experimentally based on several infusions.

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The accurate modelling of residual stress in thermoset composites requires comprehensive consideration of all the phenomena contributing to its formation. These include: chemical shrinkage of matrix due to cross linking of molecules, mismatch of thermal expansion or contraction among fibres and matrix and viscoelastic relaxation during the fabrication. Thermo-physical and thermomechanical properties are altered during the curing process due to an exothermic chemical reaction. Since all the phenomena causing residual stress are strongly coupled, the solution procedure is a complex task. In this study, spring-in angle of carbon/epoxy woven composite bracket with three different thicknesses are calculated by simultaneously solving the thermo-kinetics and thermo-mechanics coupling by a finite element code COMSOL Multiphysics. Properties of composites required for numerical simulation are obtained using an analytical method. The spring-in angle values obtained by numerical simulation are also compared with the results of the analytical model.

Properties of resin and composite, especially anisotropic coefficients of thermal expansion, are very crucial to precisely determine residual stress generated in a composite part. No comprehensive study is available in the literature to determine these properties for woven composites and then its application to model residual stress in woven carbon epoxy composite parts. In the present article, experimental results on thermal coefficients of RTM6 epoxy resin as well carbon/epoxy woven composites obtained using different experimental techniques are compared with homogenised coefficients of thermal expansion results. Evolution of spring-in angle of L-shaped carbon/epoxy woven composite (during and after cure) with three different thicknesses is modelled by simultaneously solving the thermal-kinetics and thermal-chemical-mechanics coupling by using finite element code COMSOL Multiphysics. Objective was to quantify the contribution of curing and cooling to the formation of residual stress. Anisotropic properties of composite, during and after cure, required for numerical simulation are obtained using an analytical method. Variation in properties with degree of cure and thermal gradients induced in the part during fabrication are considered while modelling. Modelled properties of cured composites were compared with experimental values and were found in agreement. The spring-in angle values obtained by numerical simulation are compared with the results of the analytical model as well as experiments. Effect of variation of fibre volume fraction and presence of thermal gradients on spring-in was studied as well.