EXPERIMENTAL-ANALYSIS AND SIMULATION OF FLOW-THROUGH MULTILAYER FIBERREINFORCEMENTS IN LIQUID COMPOSITE MOLDING

Liquid composite molding (LCM) is a process in which a reactive fluid is injected into a closed mold cavity with preplaced reinforcement. Co mbined layers of different permeabilities are often used in LCM, which creates through thickness and inplane porosity and permeability varia tions. These inhomogeneities may influence the flow front profile in t he thickness direction. To investigate the effect of the through thick ness inhomogeneities, mold filling experiments were performed using pr eforms containing layers of two different fiber architectures. Aqueous corn syrup solutions were injected into a tempered glass mold contain ing the reinforcement stack. The progress of the flow front at various locations within the reinforcement was measured by an electrical cond uctivity technique based on the insertion of small wires between the r einforcement layers. Experimental data reveal the details of the flow front shape as the fluid penetrates the preform. Using these data. a m odel is proposed to calculate the overall in-plane permeability of the preform. Numerical simulations of the flow front progression performe d with the computer software RTMFLOT developed in our laboratory are c ompared to the experimental flow front for various stacking arrangemen ts. Results show good agreement between simulations and experiments an d demonstrate the capability of the software to simulate multi-layer n ow process.