Effect of manufacturing conditions on the mechanical behaviour of short fibre reinforced PA6 parts manufactured with screw extrusion additive manufacturing

Abstract

3D printing has been increasingly used in aeronautical and automotive industry for the production of integral metallic or fibre-reinforced plastic (FRP) parts. Various additive manufacturing methods have been developed to respond to the growing industrial needs. The Screw Extrusion Additive Manufacturing (SEAM) is a pellet-based production technique relying on a heated screw extruder. This heated single screw extruder facilitates the plasticisation of injection-moulding granules and direct extrusion of high temperature thermoplastics. The mechanical properties of the 3D-printed part depend directly on adjustable process parameters, making process optimisation a strongly empirical task. To gain a solid comprehension of the process, the present article focuses on a first extensive characterization of a carbon fibre reinforced PA6 thermoplastic material with a fixed set of manufacturing parameters. The material anisotropy and fibre characteristics are first analysed on polished micrograph samples. In-situ specimens are extracted from 3D-printed parts and mechanically tested under tension, compression and bending in different material directions. In particular, the work focuses on the investigation of failure patterns through the use of the Digital Image Correlation (DIC) technique. In light of the experimental results, the article discusses potential improvements of the mechanical properties through the optimisation of manufacturing parameters.