A finite volume approach for general fully coupled anisotropic porous solid mechanics of fiber reinforcements in Liquid Composite Molding

In this work, a finite volume method is developed to capture the interaction between the infiltrating resin and the deforming fiber reinforcement in liquid composite molding (LCM). The method consists of three parts: (1) the fluid flow through a porous medium, which depends on the fiber volume fraction (FVF) and the fiber orientation, (2) the solid mechanics of the porous fiber structure considering the general anisotropic material stiffness, which also depends on the FVF and the fiber orientation, and (3) an internal coupling approach to couple porous solid mechanics and fluid flow with an iterative scheme. An anisotropic model of porous solid mechanics is proposed and verified in a unidirectional case to capture fluid-induced deformations of the porous medium. In a second verification case, the stress state is verified in an open-hole tensile test against an analytical solution for different degrees of material anisotropy. Finally, the infiltration and compaction predictions of the model are validated against experimental data from the literature using a three-dimensional plate. In addition, the infiltration behavior with the anisotropic model is compared to the isotropic model to illustrate the advantage of the new approach.