Three-dimensional (3D) printing with continuous carbon-fiber-reinforced polymer (C-CFRP) composites is under increasing development, as it offers more versatility than traditional molding processes, such as the out-of-autoclave-vacuum bag only (OOA-VBO) process. However, due to the layer-by-layer deposition of materials, voids can form between the layers and weaken some of the parts’ properties, such as the interlaminar shear strength (ILSS). In this paper, a novel mold-less magnetic compaction force-assisted additive manufacturing (MCFA-AM) method was used to print carbon nanofiber (CNF) z-threaded CFRP (ZT-CFRP) laminates with significantly improved ILSS and reduced void content compared to traditional C-CFRP laminates, which are printed using a no-pressure 3D-printing process (similar to the fused-deposition-modeling process). The radial flow alignment (RFA) and resin-blending techniques were utilized to manufacture a printing-compatible fast-curing ZT-CFRP prepreg tape to act as the feedstock for a MCFA-AM printhead, which was mounted on a robotic arm. In terms of the ILSS, the MCFA-AM method coupled with ZT-CFRP nanomaterial technology significantly outperformed the C-CFRP made with both the traditional no-pressure 3D-printing process and the OOA-VBO molding process. Furthermore, the mold-less MCFA-AM process more than doubled the production speed of the OOA-VBO molding process. This demonstrates that through the integration of new nanomaterials and 3D-printing techniques, a paradigm shift in C-CFRP manufacturing with significantly better performance, versatility, agility, efficiency, and lower cost is achievable.
DESIGN TOOL FOR DISCONTINUOUS RESIN PATTERNS IN VACUUM BAG-ONLY PREPREGS
Discontinuous resin distributions facilitate transverse air removal in vacuum bag-only prepregs during out-of-autoclave processing, and enable robust manufacturing. Methods to create discontinuous resin distributions with various pattern types and feature sizes have been demonstrated in recent reports. However, this new capability has expanded the design space for prepreg manufacturing, and optimum pattern characteristics have not been identified. In this work, a geometric model was developed to simulate prepregs and laminates with discontinuous resin distributions of various pattern type, feature size, stacking orientation, and ply count. Key metrics were employed to explore the capacity for air evacuation at room temperature. In particular, the projected surface area exposed was calculated to examine the fraction of uninhibited transverse air evacuation pathways. Secondly, sealed interfaces corresponding to the percentage of closed interlaminar regions within laminates were estimated. Finally, the tortuosity (the ratio of actual average gas transport path to straight-line path) of the dry pore network was calculated. A full factorial design, analyzed by n-way ANOVA and multi-comparison tests, was conducted to reveal the aspects of prepreg designs having the greatest influence on these metrics. Finally, these insights were used to fabricate prototype prepregs and experimentally measure their transverse permeability. Results revealed that a large number of sealed interfaces and high tortuosity were associated with lower permeability, indicating that these metrics can be used to screen resin patterns using the developed model. Broadly, the results validated a methodology to differentiate between discontinuous resin patterns with regards to air evacuation of the prepreg at room temperature, and therefore reduce the design space. Ultimately, this work can be used to guide prepreg design and to support manufacturing of high-quality composites by out-of- autoclave methods.
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- Award ID(s):
- 1827788
- NSF-PAR ID:
- 10178836
- Date Published:
- Journal Name:
- Proceedings of the Composites and Advanced Materials Expo (CAMX)
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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