Local reinforcement of thermoplastic polymers via roboticallyplaced continuous fibre tow

摘要

An integrated injection moulding process has been developed that combines the design freedom, costefficiency, net-shape processing, and the existing infrastructure of injection moulding with roboticallyplaced unidirectional (UD) thermoplastic composite yarns. Optimisation of the off-line tow placementprocess was performed and the mechanical properties and failure mechanisms studied. Increased towplacement rates increased porosity but actually also increased the UD tow tensile strength. Followingthe off-line tow placement process, the UD materials were warmed to facilitate interfacial healingduring the over-moulding process. The UD materials, together with a metallic bush incorporatedduring tow placement, were placed in the over-injection moulding tool and over-moulded. UD towinserts increased stiffness and strength by 60% to 118% and 62% to 202% for UD tow volumefractions of 18% and 36%. The over-moulding process reduced the UD tow porosity from typically44% to 130%, for the two extremes of tow placement conditions.