DcAFF (Discontinuous Aligned Fibre Filament) - Mechanical properties investigation on multilayer 3D printed parts

DcAFF (Discontinuous Aligned Fibre Filament) is a novel thermoplastic filament developed for 3D printing. This filament is reinforced with highly aligned discontinuous fibres and is based on the High Performance Discontinuous Fibre (HiPerDiF) method which produces thin tapes suitable for a range of different composite manufacturing processes. The HiPerDiF, using fibres longer than the critical length, provides mechanical performance comparable to continuous fibre composites with the high formability typical of short fibre composites. Thanks to the development of the third-generation HiPerDiF machine and the DcAFF filament forming method, circular DcAFF filaments can be produced consistently and at high rates. In this paper, both the physical properties and the internal architecture of the produced filament were investigated. In particular, mu CT scanning and image post-processing were used to quantify fibre alignment. The designed filament-forming process ensures that the large fraction of the fibres in the final product are well aligned with the longitudinal axis of the filament. The mechanical properties of the multilayer DcAFF 3D printing part are presented for the first time in this paper with tensile, short beam shear (SBS), and open-hole tensile testing. The comparison with the previous studies and data in the literature shows comparable or indeed superior stiffness of DcAFF over existing methods for 3D printing composite parts; however, to be able to consider this material as a viable candidate for high-performance 3D printing further improvements are required in term of strength, e.g. increasing fibre-matrix adhesion or substituting the proof-of-concept PLA matrix with a high performance one.