A dynamic pressure strategy to minimize void formation in vacuum infusion

Abstract An improved vacuum infusion (VI) process, called dynamic pressure molding (DPM), has been proposed to reduce void formation during infusion. In this method, the conventional VARTM process is modified by mounting a rigid chamber on top of the mold. The compaction pressure on the vacuum bag and the infusion pressure are independently and dynamically controlled during infusion to achieve the optimal impregnation for avoiding void formation. To reduce the postinfusion time, the premature sealing of the inlet, the heated air compression, and the two-sided drainage are also used in the DPM. Two different characteristics of the preform are tested at various infusion strategies. A one-dimensional nonisothermal filling model coupled with preform deformation is performed to numerically analyze the complete filling process. Results show that the four-step DPM enables at least 96.53 % of the infusion phase to be within the optimal infusion mode, but its effectiveness in reducing the total filling time depends on the preform characteristics. Several limitations of the DPM are interpreted. For comparison purposes, the typical VI process is also modeled.