On the critical technological issues of CFF: enhancing the bearing strength.

This research activity deals with 3D printing composites fabricated by Continuous Fiber/Filament Fabrication with an innovative thermoplastic matrix infilled with microcarbon fiber, i.e., Onyx, and carbon reinforcement. Three groups of additively manufactured samples were printed and tested to evaluate the possibility of avoiding the drilling phase to increase the bearing resistance and evaluate the parts' properties: standard geometry, post-process drilling, and customized geometry. Different configurations were realized for the additively manufactured and drilled samples to assess the reinforcement effect on the bearing performance and identify the 3D printing technology limits. Finally, the customized sample represents a new approach to conceiving a better solution for enhancing the bearing strength. Pin-bearing stress and stiffness have been analyzed through experimental methods, the material compaction quality was detected by ultrasound technique, and failure modes have been discussed. Concerning the additive samples, the bearing strength decreased in all reinforced printed configurations due to the technological limitations of the CFF process. However, exploiting a more flexible approach in the design, a novel bearing configuration with a custom infill strategy was proposed, reaching high values of bearing strength and stiffness. This resulted in a reduction in costs and weight, taking one step toward more sustainable production. [ABSTRACT FROM AUTHOR]