FFF-based 3D printing path design of interconnected microchannel network inside continuous fibre-reinforced composites for thermal manipulation

Microchannel networks present remarkable advantages in the field of thermal management and significantly boost performance by augmenting the heat transfer capabilities of composite materials. In this study, a pioneering 3D printing path design technique based on FFF (Fused Filament Fabrication) is introduced. This innovative method enables the fabrication of microchannel networks within continuous fibre-reinforced thermoplastic (CFRTP) composites without severing the fibres. Unlike traditional micro-drilling or wire embedding techniques, it has the potential to form elliptical holes with precisely oriented continuous fibres that conform to load transmission paths. Experimental results indicate that this approach can reduce the strain concentration factor of conventional circular holes by a substantial 70 %. Additionally, the printing paths of multiple layers are synchronized to intricately construct interconnected and bifurcated Y-shaped microchannel networks. The integration of GaInTi liquid metal within these microchannels has led to a notable 49 % enhancement in the thermal conductivity of CFRTP samples, even though the microchannel areas constitute only 1/1076 of the entire 700 mm² testing area.