Self-heating consolidation method for 3D-printed continuous wire polymer composites

The use of fused filament fabrication (FFF) for 3D printing of continuous fibre composites has significantly improved composite manufacturing. With its ability to manufacture geometrically complex, high strength composites, parts that would have not been achievable through traditional composite manufacturing methods can now be explored. 3D printers that print continuous metal wires have been prominent in recent research because of their wide range of applications including sensing and shape memory behaviour. Previous studies in the field of 3D-printed continuous wire polymer composites (CWPCs) have identified the presence of voids around the wire reinforcement location but have not addressed mitigation techniques. Voids can significantly decrease adhesion between the matrix and reinforcement material, causing a decrease in strength and stiffness. Traditional composite manufacturing methods, such as hot-pressing or compression molding, are used to decrease voids after manufacturing. In this study, continuous nickel-chromium wire thermoplastic composites are manufactured using FFF 3D printing. This study develops a consolidation procedure which utilizes the principles of hot-pressing and resistive heating, accompanied by thermal modelling of the transient conduction and resistive heating of the sample. Optical microscopy and three-point flexural tests are carried out to quantify the void volume fraction, as well as the flexural strength and flexural modulus after the consolidation procedure is performed. Void content was found to be decreased by 63.9% and 91.6% after hot-pressing and consolidation, respectively. Three-point flexural test results show that the consolidated samples displayed a 5% and 12% increase in flexural strength and modulus, respectively.