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In this present study, the fused deposition modeling (FDM) method was used to fabricate the composites. Before three-dimensional (3D) printing, samples were designed according to the ASTM D256, D790 and D3039 standards for impact, flexural and tensile tests, respectively, using Onshape software before conversion to an STL file format. Afterward, the digital file was sliced with infill densities of 60%, 80%, and 100%. The composite samples contained chopped carbon fiber (cCF) and poly lactic acid (PLA), as reinforcement and matrix, respectively. The cCF/PLA (simply called cCFP) filaments were printed into various cCFP composite (cCFPC) samples, using a Viper Share bot 3D machine with different infill densities before the aforementioned mechanical testing. The tensile strength of cCFP were obtained as 25.9MPa, 26.9MPa and 34.75MPa for 60%, 80% and 100% infill density cCFP samples, respectively. Similarly, the flexural strength of cCFP were obtained as 11.8MPa, 12.55MPa and 18.4MPa and impact strength was 47.48kJ/m2, 48.45kJ/m2 and 48.96kJ/m2 for 60%, 80% and 100% infill density cCFP samples, respectively. The fractured/tested samples were examined and analyzed under a scanning electron microscope (SEM) to investigate the presence of fiber and void in the tensile sample. Based on the experimental results, it was evident that a high infill density of 100% with the highest reinforcement exhibited maximum impact strength, tensile and flexural strengths and moduli when compared with other lower carbon content of cCFPC samples. Therefore, the optimal 3D-printed cCFPC sample could be used for engineering application to benefit from properties of the polymer matrix composite materials and possibilities through additive manufacturing (AM). [ABSTRACT FROM AUTHOR]

To overcome the dependence of continuous carbon fiber reinforced thermoset composites (CCFRTCs) on molds during the curing, a thermoset continuous fiber prepreg filament and thermoplastic filament alternate printing method was proposed. CCFRTCs with thin thermoplastic shells were prepared based on the method, and the confinement of thermoplastic shells enabled the mold‐less curing of CCFRTCs. The influence of key curing process parameters on the flexural properties of the specimens was systematically investigated. The experimental results showed that the flexural properties of the prepared composites were correlated positively with the vacuum degree and showed a tendency of first increasing and then decreasing with the increasement of impregnation time and curing temperature. Through x‐ray computed tomography (CT) and scanning electron microscope (SEM) analysis, the effect of key curing process parameters on the flexural properties of the CCFRTCs was clarified. Under the guidance of suitable curing process parameters, the flexural strength and modulus of the composite reached 482.89 MPa and 35.11 GPa, which were significantly better than most existing 3D printed continuous carbon fiber reinforced polymer composites. Finally, complex components were prepared to verify the feasibility and versatility of the technique. Highlights: A CCFRTCs mold‐less curing method was proposed.The effect of key parameters on the properties of CCFRTCs was clarified.Both the advantages of thermoset and thermoplastic materials were obtained.Complex components with low porosity were prepared. [ABSTRACT FROM AUTHOR]