Evaluating addition of a membrane layer in vacuum infusion processing of fiber reinforced epoxy composites in terms of flexural properties and void content

The effect of addition of a membrane layer in vacuum infusion process was investigated with emphasis being placed on the flexural properties and void content of the resulting composites. E-glass fiber and epoxy were, respectively, used as filler and matrix constituents to produce the composites. Conducting a facile TGA based methodology, fiber volume fraction, density, and void content measurements were carried out on the samples taken from different zones across the composite parts. Despite giving rise to the composite thickness, 16 % high compared to the part thickness produced by vacuum infusion without any membrane, infusion with incorporation of the membrane layer resulted in a relatively high composite fiber volume fraction with reduced void content at no expense of compaction. At the vacuum port, flexural strength and modulus values of the composites produced by membrane added vacuum infusion process (MAVIP) were found to be, respectively, 11 and 8 % higher than those of the composites produced by conventional vacuum infusion process (CVIP). On the other hand, at the inlet port, composites produced by MAVIP exhibited 12 and 9 % high flexural strength and modulus values compared to those produced by CVIP. Moreover, the load-deflection response (P/ d ) of the samples taken from different zones along the parts was correlated with respect to their length-to-width aspect ratio (L/b) based on the plain strain analytical approach. Once L/b aspect ratio was greater than 6.5, plain strain approach was found to converge to more definite beam modulus values, regardless of the process used.