Mechanical properties of additively manufactured composite materials with ultrasonically assembled reinforcement

This study demonstrates the use of ultrasonic manipulation to assemble short fibres into a desired orientation within a photocurable resin, in order to additively manufacture discontinuous fibre reinforced composite materials. An optimised postcure time of 5 minutes was determined, as well as a suitable fibre weight fraction of 0.05 g/ml, which would demonstrate anisotropy without significantly hindering either the alignment or printing processes. Samples were fabricated from neat resin, as well as fibre reinforced samples. All fibres were unidirectionally aligned, with one set of samples containing fibres aligned at 0^◦ to the loading axis, and another set containing fibres aligned at 90^◦ to the loading axis. These materials have subsequently been loaded in tension to failure, with the ultimate tensile strength and Youngs modulus subsequently calculated. A 103% increase in tensile strength and 64% increase in Youngs modulus was found with 0^◦ fibres compared to the neat resin. An increase of 76% and 94% was observed between samples with fibres aligned along the loading axis and those with fibres aligned at 90^◦ to the loading axis.