Influence of processing variables on quality of unsaturated polyester/E-glass fiber composites manufactured by double-bag progressive compression method

Abstract

A hybrid process of articulated resin transfer molding and vacuum-assisted resin infusion, called double-bag progressive compression method, has been invented to fabricate composite parts. In double-bag progressive compression method, the secondary bag is divided into several segments. During resin infusion, the double bag is drawn upward by vacuum, and the initial flow resistance offered by the loose preform is low. Once the resin infusion is completed, the vacuum on the segmented bags is progressively released to ambient pressure, and the segmental compression is sequentially performed until unnecessary resin is completely removed. This research is to experimentally investigate the influence of double-bag progressive compression method processing parameters, including vacuum pressure in the cavity, number of segments, initiating time of the next compression, temperature of the heated air, initiating segment of the heated air, initial height of the mold cavity, and excess infused resin, on the mechanical property of the part. The design of experiments adopts Taguchi’s method. Results show that the double-bag progressive compression method significantly reduces total filling time and maximally increases the flexural modulus of the part by 17.81% as compared with the typical vacuum-assisted resin infusion. A preferable parameter condition is proposed by taking both the flexural modulus and the operation complexity into account.