Static and dynamic mechanical performance of short Kevlar fiber reinforced composites fabricated via direct ink writing

Additively manufactured polymer composites have advantages over those fabricated traditionally due to their improved design flexibility, short time frame of design-to-manufacturing process and reduced material waste and investment cost. Additive manufacturing of short fiber reinforced thermoplastic composites has been well investigated recently, and their mechanical performance has been well characterized. Additive manufacturing of thermoplastic composites, however, has unresolved, high porosity and low mechanical performance issues. In this study, we investigated the feasibility of using of a customized, vibration-integrated, direct write additive manufacturing setup to fabricate short Kevlar reinforced epoxy composites. Highly viscous composite inks (max. of 6.3% Kevlar fiber) were successfully extruded and 3D-printed on a print bed, at room temperature. The mechanical performance of the printed composites was examined and compared to that of unreinforced base ink specimens by performing static and dynamic 3-point bending experiments. It was observed that additively manufactured, thermoset-based, short Kevlar fiber reinforced composites possess the mechanical performance surpassing the previously reported short Kevlar fiber reinforced thermoplastic composites and near to that of continuous fiber reinforced composites. Considering their high mechanical performance in addition to low weight, and high ductility, these composite materials have a great potential to find novel structural applications in the near future.