Additive manufacturing of continuous carbon fiber/epoxy composites with structured core-shell towpreg: Methods, characterization, and mechanics

Abstract

Continuous carbon fiber thermoset composites are acclaimed for their exceptional structural integrity, environmental durability, and extended service life, yet their additive manufacturing (AM) has been relatively underexplored. This study investigates the mechanical performances of 3D-printed continuous carbon fiber/epoxy composites fabricated using the Tow-Preg Cladding (TPC) method. This novel approach integrates in-situ epoxy impregnation, dual-cure cladding, and tow-preg deposition to enhance the producibility of such composites via AM. The resulting composite showcases a fiber volume fraction exceeding 50 %, offering remarkable mechanical properties. We report a tensile strength of 1295.72 MPa, a compressive strength of 544.13 MPa, a flexural strength of 659.30 MPa, and an interlaminar shear strength of 50.87 MPa. Furthermore, the tensile strength and modulus achieved 41.5 % and 58.1 % of the values predicted by a modified rule of mixture equation, indicating competitive performance among various AM systems for continuous fiber composites. By addressing challenges in uniform fiber distribution and optimizing composite morphology, this research marks a significant advancement in AM for thermally curable thermoset composites. The comparative analysis of diverse AM techniques positions our TPC approach as a promising solution in the field, potentially transforming future high-performance composite fabrication.