Carbon-fiber reinforced polymer composites: A comparison of manufacturing methods on mechanical properties

Carbon-fiber reinforced polymer composite materials are used throughout industry for their excellent mechanical properties; in particular, these composites boast high specific stiffnesses and specific strengths. However, current limitations on manufacturing, which vary greatly based on the technology that is utilized, restrict access to composite materials in a variety of applications. Traditional wet hand-layups offer a large diversity of viable constituent materials, but the fabrication geometry is limited and the manual process is time-consuming. In contrast, fiber 3D-printing (F3DP) allows for the production of complex geometries and requires little manual labor. In this study, laminates with continuous carbon fiber reinforcement printed using a commercially-available 3D printer are compared to carbon fiber fabric-resin composites produced using manual layup techniques. Cross-ply [0,90,0,90,0]T laminates were fabricated and subject to mechanical testing in uniaxial tension and flexure. After normalization with respect to fiber volume fraction, we found that the tensile strength and stiffness of cross-ply carbon fiber composites manufactured using F3DP were higher than the tensile strength and stiffness of cross-ply specimens manufactured by a traditional hand-layup method; however, the hand-layup specimens exhibited higher strength and stiffness in flexure. The difference in material properties evident between the two fabrication methods suggests that each has its own suitable application. We anticipate that further studying the failure response of printed, fiber-reinforced composite materials to various loading modalities will give insight into potential areas of improvement for F3DP material selection and printing processes, particularly relating to void reduction. On a broader scale, comparing and analyzing the mechanical properties of composite laminates produced in these various methods will provide perspective on the viability of novel additive manufacturing methods for large-scale production and industrial applications.