Adaptive Control of Filling Pattern in Resin Transfer Molding Process

Abstract

During the Resin Transfer Molding (RTM) process, the filling pattern is strongly affected by race-tracking phenomenon and this usually leads to dry spot formation at the end of the filling stage and results in defective parts. This situation can be alleviated by placing air vents at the locations of the Last Point to Fill (LPF), where dry spots usually form. However, due to the variation of the race-tracking effects, the LPF location does not remain in the same position during RTM batch cycle production. Dry spots can still form and the part is still scraped. In order to ensure that the LPF location always coincides with the predetermined vent during RTM batch cycle production, an adaptive control strategy based on a model reference adaptation system that can regulate the LPF location during the RTM filling stage is proposed, to adjust the inlet pressures on-line. Multiport flow is simplified as many individual one-dimensional ‘spine’ flows and each ‘spine’ extends from the gate to the vent along the short path. The spine flow is controlled independently by adjusting the pressure of the related inlet. The control input is the distance between the inlet and the flow front along the spines, and the reference model of the flow is that the resin is driven by a uniform velocity from the gate to the vent along the spine. The proposed adaptive control has the capability to adapt to high levels of system disturbances. The proposed adaptive control is tested numerically by incorporating the control algorithm into a RTM time-implicit filling simulation. The resulting simulations show that the proposed control strategy can eliminate the dry spot formation under a wide range of situations resulting from the variations in the race-tracking effects.