Development of Virtual Process Simulation and Validation for a Carbon Fiber Reinforcement Panel

Abstract

Carbon fiber reinforced polymer composites (CFRP) are increasingly utilized in aerospace and automotive industries for lightweight structural applications due to their excellent properties. However, challenges remain in the molding of structural composite parts having a high fiber content with a short cycle time. The permeability of the fabric reinforcement decreases exponentially as the fiber content increases, leading to a long filling time when low pressure injection is used. This, in turn, causes resin gelation during the filling stage resulting in partially filled parts due to the long filling time. High Pressure Resin Transfer Molding (HP-RTM) is a recent variant of Resin Transfer Molding (RTM) technology that enables a high resin injection rate and thus a short cycle time when new fast curing resins are used. In this work, a carbon fiber reinforcement panel of an all-carbon fiber floor assembly is successfully designed and fabricated using HP-RTM. To better understand the physics of the resin flowing through a porous fiber bed, which is the fundamental aspect of the HP-RTM process, this paper discusses the Finite Element Analysis (FEA) development used to predict the location of the resin flow front, the in-mold resin pressure profile, and the degree of cure of the resin with selected continuous carbon fiber fabrics. The developed FEA framework is used to guide the tool design and determine the locations of the injection gates and vacuum ports. We have developed a semi-automated molding procedure by synchronizing the press and HP-RTM metering control system to enable the stepwise vacuum and injection strategy while a predetermined tonnage is maintained. The reinforcement tool is equipped with in-mold pressure sensors and dielectric cure sensors for data acquisition during molding. The correlation between the experimental data and simulation predictions shows good agreement regarding the resin filling time and the in-mold pressures during the resin injection phase. An overall cycle time of 3 minutes is successfully achieved to mold the reinforcement component.