Numerical Simulation And Experiment Study On Resin Filling Of Fiber Reinforced Composites With VARTM Process

Vacuum Assisted Resin Transfer Molding (referred to as VARTM), one of theLiquid Composite Molding (LCM) techniques, is an adaptation of the Resin TransferMolding (RTM) process. It is cost effective and suitable for large and complexstructures such as structures with insert, ribs and core. Vacuum pressure not onlyprovides the main driving force for performs impregnation, and also draws out theentire air and moisture. So the VARTM process can produce composite with highquality.The numerical simulation and experiment for the resin flow behavior in theVARTM process has been studied in the paper. The purpose is to provide theoreticalfoundation for shortening the molding cycle and improving product quality. The maincontents and results are summarized as follows.Firstly, the rheological properties of the vinyl resin system have been studiedsystematically. The dynamic viscosity characteristics, isothermal viscositycharacteristics and the effect of temperature on gel characteristics have been analyzed.Furthermore, by data fitting method with the experimental data, a mathematicalmodel to predict the viscosity of vinyl resin system has been obtained.Secondly, the permeability of fabric and infusion media has been studied. Thepermeability of the unidirectional fabric(0°), biaxial fabric (±45°), biaxial fabric(0°/90°) and VI160-type infusion media have been tested respectively, which isprovided for numerical simulation and experimental study.Thirdly, with RTM-Worx, a professional resin transfer molding processsimulation analysis software, the flow behavior of resin in VARTM process has beensimulated. The visual VARTM experimental platform has been built up. Bycomparing the simulation results with the experiment results, the effect of fivetechnological parameters (resin viscosity, injection type, vacuum pressure, infusionmedia and stacking layers of fabric) on resin flow behavior has been showed,providing a reference for developing process.Finally, the samples have been fabricated by the VARTM process with different type of fabric (unidirectional,±45°and0°/90°) and in different stacking layers (3,6,9and12). The effect of different type of fabric and different stacking layers on fibervolume fraction and void content has been studied. Experimental results show that thethicker samples show greater fiber volume fraction and less voids. The sample withunidirectional fabric has maximum fiber volume fraction, achieving51.85%; whilethe sample with biaxial (0°/90°) fabric has minimum fiber volume fraction, reaching44.83%. The sample with biaxial (±45°) fabric shows least voids, with only about2.96%, however, the sample with unidirectional fabric shows maximum voids, withabout4.0%. Therefore, high quality composites can be fabricated by rational plydesign.