Towards Sustainable Structural Joints: High-Strength Induction Welding of Recycled Carbon Fibre Composites

<jats:p>Re-introducing recycled carbon fibre (rCF) into the manufacturing value chain signifi-cantly reduces environmental impacts. The fabrication of nonwoven mats made by card-ing rCF with thermoplastic filaments enable the production of preform suitable for manu-facturing and thermoforming structural parts and fusion bonding technologies. The in-duction welding process takes advantage of the random nature of such materials since the discontinuous fibres contribute to the formation of microcircuits heated by the eddy cur-rents related to the magnetic field enabling a susceptor-less welding process. In this paper, the optimal welding parameters of induction welding of rCF/maleic anhy-dride-grafted polypropylene (MAPP) laminates are been investigated. The compression molded laminates have been consolidated and experimentally characterized for compari-son with welded joints. The strength and fracture behaviour of the welded joints are gov-erned by several process parameters, including generator power, coil distance, translation speed, and compaction load. The optimal condition yielded an interlaminar shear strength of 11.7 ± 0.6 MPa, at least equal to that of the parent laminate. A Mode I initiation tough-ness of 560 ± 207 J/m² was measured, and all the joints failed cohesively. The actual welded area inside the joint is function of the welding process. The uniformity of the conductive fibre network was found as the key parameter on the extent of the weld. Although the weld was not uniform across the configurations, the findings support in-duction welding as an effective joining method for rCF nonwoven laminates.</jats:p>