Abstract: The comprehensive performance of hybrid fiber composites is significantly superior to that of single fiber composites. As a core parameter characterizing the impregnation ability of fibers, permeability directly affects the quality and mechanical properties of products. In this paper, a combined method of numerical simulation and experiment is adopted to study the equivalent permeability of hybrid fiber composites. A two-scale porous medium unit cell model considering the porosity within fiber bundles is established, and the reliability of this approach is validated by experimental findings. The influencing factors of fiber type, layering method, and nesting effect on the equivalent permeability of the unit cell are investigated. The results show that an increase in carbon fiber content in the unit cell significantly reduces the equivalent permeability of the unit cell; under different layering sequences, the low permeability layer inhibits fluid flow in the high permeability layer, thereby reducing the equivalent permeability of the unit cell; the nesting effect reduces the internal porosity of the fabric and increases the curvature of the flow channel, leading to a significant decrease in the equivalent permeability of the unit cell.

Key words: hybrid fiber, two-scale porous medium, equivalent permeability, unit cell model, nesting effect