Integrating additively manufactured continuous glass fibre inserts in compression moulding: A novel approach to mitigating fibre–matrix separation effect

Abstract

This study presents a novel approach to mitigate fibre–matrix separation defects in compression-moulded thermoplastic composite components by integrating additively manufactured (3D-printed) continuous fibre-reinforced inserts into the stiffener ribs. The design of these inserts was guided by topology optimisation and refined to align with additive manufacturing principles. The feasibility of embedding 3D-printed inserts was demonstrated, yielding hybrid parts with consistent quality, accurate positioning, and a defect-free insert/moulded part interface. Mechanical testing under three-point bending revealed substantial performance gains: stiffness, strength, deflection, and energy absorption improved by factors of up to 1.5, 3.5, 1.4, and 12, respectively. A 45 % reduction in insert thickness further enhanced manufacturability and interfacial bonding, shifting the failure mode from interfacial delamination at the rib base to fibre rupture at the rib tip. Despite the reduced material volume, stiffness decreased by only ∼17 %, while strength remained stable and toughness improved significantly.