Post-consolidation process for modifying microscale and mesoscale parameters of 3D printed composite materials

Advancements in additive manufacturing technology (3D printing) have enabled us to fabricate reasonably good parts using continuous fiber-reinforced matrix composites. Unfortunately, most of these 3D-printed composite parts inherently possess a large number of voids originating from the trapped air within and between molten composite beads during the deposition stage. Removing the voids has thus become a key challenge in attempts to apply 3D printed composite parts for fabricating stiff/strong load-bearing structures. Here, we employed a classical process, viz. compression molding, to post-consolidate 3D-printed continuous carbon fiber-reinforced polyamide (CFPA), and to investigate the implications in terms of microscale parameters (void content) and mesoscale parameters (mechanical properties, plasticity, damage) using matrix-dominated lay-up of [±45]_2s. We found that the proposed post-consolidation process could reduce the void of 3D-printed CFPA from 12.2% to 1.8%, enhancing the shear modulus and shear strength by 135% and 116%, respectively. The mesoscale analysis shows that, albeit with less ductility, the post-consolidated CFPA laminate was more resistant to damage than the 3D-printed CFPA. Classical compression molding is thus a promising technique for improving the physical and mechanical performances of 3D-printed composites by reducing inherent void built-ups.