Numerical modeling of suspension impregnation in fibrous media: application to the VARI process

Abstract Resin infusion processes are essential in manufacturing high-performance composite materials, providing a cost-effective and scalable method for producing complex fibre-reinforced structures. Among these, vacuum-assisted resin infusion (VARI) is especially valued for its ability to produce void-free laminates with minimal tooling and pressure. This article introduces a numerical model designed to simulate the impregnation of a fibrous medium with a particle-filled resin (suspension), specifically tailored to the VARI process under atmospheric pressure. To date, this infusion method has not been extensively explored in the literature, particularly with regard to suspended particles. The model aims to accurately replicate mold filling behavior, considering both suspension flow dynamics and particle retention mechanisms. Validation was performed using both analytical and numerical benchmarks, producing consistent and reliable results. An advanced parametric study was conducted to evaluate how key process parameters such as initial concentration, vacuum pressure, and fiber volume fraction affect the dispersion of particles during infusion. A comparative analysis of VARI and RTM processes further underscored the unique flow behavior of particle-laden flow under vacuum. The results demonstrate that the final particle distribution within the composite strongly depends on the initial concentration, the travel distance of the flow front, and the fibre volume fraction relative to the cavity geometry, providing valuable insights for the precise control of reinforcement architecture in functional composite manufacturing.