Abstract
<p>Direct ink writing is a robust additive manufacturing technology for the fabrication of fiber reinforced thermoset composites. However, this technique is currently limited with low design complexity and minimal heights. This study aims to investigate the feasibility of UV-assisted direct ink writing of composites to enhance the green-part strength of the printed inks, resolve the complexity and the height limitations of direct ink writing technology, as well as test the viability of printing continuous carbon fiber. The experimental approach involved preparation of the thermoset inks that are composed of nanoclay, epoxy, photopolymer and reinforcement. Short fiber composite specimens were fabricated in complex geometries from these ink feedstocks and continuous carbon fiber samples were successfully printed using UV-assisted hybrid 3D-printing technology. Short fiber specimens were characterized using optical microscopy and 3-pt bending mechanical tests. The introduced UV-assisted 3D-printing technology allowed the fabrication of tall and overhanging thermoset composite structures up to 30% glass fiber reinforcement, without sagging during or after printing. Glass fiber reinforcement tremendously enhanced the mechanical performance of the composites. The UV curable resin addition led to the reduction in strength (~15%) compared to composites fabricated without UV resin. However, this reduction can be eliminated by increasing the glass fiber content within the hybrid thermoset composite. This study showed that the fabrication of high-performing thermoset composites in complex geometries was possible via hybrid direct ink writing technology. This study also showed the viability of using UV-assisted DIW to print continuous carbon fiber samples<br />
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