The preform is covered by a flexible vacuum bag in vacuum-assisted resin infusion process, and the preform compaction state is time and space dependent during the mould-filling stage, there is no practical tool for the filling simulation. In this paper, the resin flow governing equations for vacuum-assisted resin infusion are built based on the analysis of the preform compaction behaviour and the fibre tow impregnation. For obtaining the numerical solution conveniently and accurately, an alternative approach is proposed in which the primary flow is computed from the normal Darcy's law, two-slave elements are added to each master element, named sink slave element and deformation slave element, to calculate the resin mass variation caused by fibre tow infiltration and preform deformation. Three examples are conducted to verify the precision and broad applicability of the approach. The influence of the preform deformation and the unsaturated effect on the mould filling is analysed.

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Resin infusion (RI) process has been widely used for manufacturing composite parts. The variation of preform thickness brings great difficulty to the three-dimensional simulation of the filling stage. To accurately simulate the preform thickness change and resin flow during resin infusion, precise preform compaction models and dynamically changing geometry models need to be adopted. At present, resin flow is usually considered as two-dimensional and simple compaction models are employed to simplify the simulation, which degrades the prediction accuracy seriously. In this paper, general equations to describe the resin flow in the changing thickness cavity are developed, and the viscoelastic model is adopted which can fully express the dynamic characteristics of the preform compaction. To avoid solving the coupled resin flow/ preform deformation equations directly, the volume of fluid method and the dynamic mesh model are employed to implement the tracking of the flow front and updating of cavity geometry model. The resin storage and release induced by porosity variations are adjusted by a master-slave element method to ensure mass conservation. Two simulation examples are carried out to demonstrate the capability of the above approach. The applicability of the approach on arbitrary complex domains and sequential injection strategy is also verified.

Compression resin transfer molding (CRTM) is an effective process for the manufacturing of composite parts with large size and high fiber content. The analysis of the resin flow and stress distributions can only be performed by directly solving the coupled flow/deformation equations, but it is difficult to handle the complicated preform deformation models and geometry models; therefore, the simulation precision and application range are extremely limited. In this paper, an alternative approach is introduced to overcome the above problems, in which the preform deformation and the accompanying resin release during the secondary compaction phase are calculated in an additional element associated with each unit of the discretized model geometry instead of solving the coupled governing equations directly, so the complex compaction models can be adopted. Three simulation examples are presented to demonstrate the accuracy and capability of the above numerical approach on velocity-controlled, force-controlled 3D CRTM processes.