Investigation of interfacial shear strength of hybrid fibre-reinforced polyamide composite structures made by fused granular fabrication and automated tape laying

Abstract

AbstractFused granular fabrication (FGF), a technology within the framework of large format additive manufacturing (LFAM), focuses on cost-effective granulate-based manufacturing, eliminating the need for semi-finished filaments. The anisotropic behaviour of 3D-printed parts is evident in their varying mechanical properties along different axes, which are amplified when fibres are incorporated into the material. In this study, a significant improvement in the flexural stiffness and strength of manufactured FGF structures and a lowering of anisotropic behaviour have been achieved through the integration of continuous fibre-reinforced unidirectional tapes (UD-tapes). With the employment of automated tape laying (ATL), UD-tapes have been applied to plate structures manufactured by the FGF process. The manufactured structures were characterised in terms of their morphology and mechanical behaviour by 3-point-bending tests. As the effectiveness of the UD-tape reinforcement requires sufficient bonding between the UD-tape and the FGF structure, the interface morphology and interface strength were investigated. Different surface preparations were considered prior to tape laying to account for the influence of the surface quality of FGF structures. It was demonstrated that UD-tape laying on an FGF surface that was prepared by a milling process provides a higher interface shear strength compared to an untreated FGF surface.