Effect of the subsidiary materials of the manufacturing process on the microstructure of the composite laminate

Abstract

Composite specimens with resin contents of 33.5%, 35.4%, and 35.9%, respectively, were manufactured by controlling the type of subsidiary material used in the bagging process for a composite material having the same composition.The effect of controlling the resin content on the microstructure and mechanical properties of composite specimens was investigated. The flow of resin and air during the cure process was inferred and explained by connecting it with the microstructure. Specifically, the behavior of the resin determined the thickness, density, and void of the composite laminate, which acted as a factor causing the difference in mechanical properties of the composite materials. As the resin content increased, there was no significant difference in tensile strength, but Young's modulus decreased. In the case of the compression test, there was a difference in mechanical properties due to the combined effect of the reinforcement and the resin. The maximum compressive strength value was shown in the process with low void content, and Young's modulus tended to decrease as the resin content increased. In the bagging process, the subsidiary material controlled the flow of resin and air, and caused a difference in microstructure, affecting the change of mechanical properties.

Effect of void formation according to resin content on composite joint area

“…In previous studies, voids were observed in the area where subsidiary materials were laminated, not on the first layered lay-up mold surface, and it was reported that these results varied according to the resin and air flow, which depended on the selection of subsidiary materials. 30 Except in Figure 5a, it was confirmed that voids were formed in the area where subsidiary materials were lay-up. Under the influence of the bagging film in the bagging process, the internal air flow continuously flows in the vacuum direction and is maintained until the cure process.…”

“…The result of the test is the average of the specimens tested under each condition. Checking the test results of the tensile laminate specimens in Table 3, the strength values of Case 1, Case 2, 30 Case 3, 30 and Case 4 30 were 514.2 MPa, 539 MPa, 534 MPa, and 536 MPa, respectively, and the young’s modulus value was 26.4 GPa, 25.9 GPa, 25.3 GPa, and 25.2 GPa, respectively. The mechanical strength property of the composite laminate specimen has a value between the reinforcement having high strength and Young’s modulus and the matrix property having low strength and Young’s modulus.…”

“…Resin content varies depending on the manufacturing process and types of subsidiary materials, and affects density and void formation. 30 Specifically, the occurrence of voids is an important factor in the quality of composites, and the formation of voids in the composite manufactured through the bagging process may vary depending on the compaction holding time and moisture absorption during the hand layup process of the prepreg. [31][32][33] Many studies on resin flow and voids have been conducted in various processes based on OoA.…”