Simulation of LCM processes involving induced or forced deformations

Abstract

Resin Transfer Molding (RTM) is part of Liquid Composites Molding technologies in which composites are manufactured by the impregnation of a stationary fiber preform by a low viscosity resin system. Competitive simulation tools for RTM modeling are widely spread in the composites world. However, other LCM processes need also to be modeled, especially those that imply deformation of the fiber bed. By using LIMS, a code initially developed to model the RTM process, has been introduced a routine that can manage forced deformations due to external stress, such as in the injection/compression process, as well as induced deformations of a non-rigid insert such as in sandwich manufacturing techniques, where the pressure of the flowing resin can locally compress the foam core. The routine implemented compares the liquid pressure profile with the mechanical properties of the solid entities and sets the deformations induced by changing geometrical features. The preform characteristics (fiber volume content and permeability) are then updated. The mass conservation principle is respected by keeping the injected amount of resin constant through an artificial injection stage. Computed pressure and deformation are compared to experimental data from injection of a sandwich structure where foam core deformation occurs and from injection of a hollowed part molded with an inflatable bladder, and with an analytical solution in the case of the injection/compression process of a cylindrical part.