AN EXTERNAL FLOW MODIFICATION SYSTEM FOR VACUUM ASSISTED RESIN TRANSFER MOLDING

摘要

Recent studies have revealed that a rigid external vacuum chamber placed over the vacuum bagrnin vacuum assisted resin transfer molding (VARTM) and SCRIMP composite manufacturingrnprocesses yields improved resin delivery within a mold. In his research, a real-time, noninvasivernmethod for controlling resin flow was modeled and tested using a lab-scale prototype.rnTo understand the basic resin flow characteristics of resin flow in the presence of an externalrnchamber that lifts the vacuum bag, finite element models were developed of the chamber andrnpreform assembly, and simulations were performed to understand the resulting effects on resinrnflow within a mold. Various mold permeability distributions were also examined. Thernsimulation results clearly demonstrated that the effects of the external chamber can be accuratelyrnpredicted. Simulation results indicate that when larger voids are present, multiple chamberrnplacements are necessary to insure full part infusion. When this situation occurs, the order of thernchamber deployment is critical for a successful injection. Reliable FEA modeling of thernchamber flow can be used for commercial implementation in which the optimal placement of thernchamber can be computed in real time during an injection by an automated, adaptive, closedlooprnprocess, when undesirable flow fronts are predicted and/or detected. Using the externalrnchamber, a robotic system has been prototyped that identifies dry regions forming duringrninjection via computer vision, deploys the vacuum chamber over the mold with a robotic arm,rnand actuates the chamber in order to modify and correct the resin flow within the mold. Testrnresults using lab-scale molds with large variations in preform permeabilities indicate that thernrobotic system can correct and/or modify the resin flow within a mold in real time, thusrneliminating dry, unfilled regions.