This work is structured in two complementary phases that link material characterization with architectural-scale fabrication. Phase 1 establishes a fundamental understanding of how raster orientation and material composition influence the mechanical and microstructural performance of large-scale 3D printed polymers. Phase 2 translates these findings into a full-scale architectural application, demonstrating how composite-inspired printing strategies can be operationalized in robotic fabrication to produce structurally informed, lightweight building components.
Phase 1: Analysis
Additive manufacturing in building construction can be extended for mass customization of building components or even complex mold making. This study examines the process parameters of raster orientation of short carbon fiber-reinforced polylactic acid (SCF-PLA) and neat PLA in large-scale 3D printing. Three raster orientations—unidirectional, cross-ply, and quasi-isotropic layups—were printed using a pellet extruder assembled on an industrial robotic arm. Tensile and flexural tests were conducted to characterize the differences between SCF-PLA and neat PLA across all raster orientations. This study shows that neat PLA has higher tensile strength compared to SCF-PLA, and quasi-isotropic orientation can improve the week mechanical properties of both SCF-PLA and PLA. This research highlights the interface bonding challenges encountered with larger 3D printed filaments, which result in more significant pores. Furthermore, any factor that modifies rheological properties of the filament, such as carbon filling, can lead to a higher likelihood of material defects. To understand this discrepancy, microstructure analyses were conducted on intact and fractured 3D printed samples, including the analysis of micro voids, interlayer voids, and bonding between SCF and the PLA matrix. This suggests that the effects of quasi-isotropic layups can be applied to enhance 3D print large-scale polymer-based building components.
This research was published in Additive Manufacturing Letters.
Phase 2: Application
Axisymmetric Column No. 1 exemplifies a novel approach to large-scale robotic additive manufacturing, utilizing curved-layer fused filament fabrication (CLFFF) on a pre-stretched textile. It explores how patterning affects CLFFF printing to develop a lightweight hybrid shell structure. The cross-ply [0°/90°] and quasi-isotropic [0°/60°/90] patterns, inspired by composite engineering, enhance the mechanical properties of SCF-PLA.
The final unit, including the shell structure and the base, has a height of 2300mm with a span of 900mm, and is reinforced by 10 kg of SCF-PLA pellets. The developed nonplanar robotic 3D printing technique was applied in reinforcing an individual axisymmetric column, which is one column out of three-column vault structure.
This application was presented at ROB|ARCH 2024 conference held at Toronto, Canada.
Project Team
Ehsan Baharlou; Ji Ma (Phase 1)
Project student research assistants
Phase1: Tabi Summers; Ipsita Datta
Phase2: Avery Edson, Juliana Jackson, Eli Sobel, and Tabi Summers
Image Credit
Ehsan Baharlou, CT .lab, University of Virginia, 2024
Acknowledgements
Support from Melissa Goldman, Dr. Trevor Kemp, and Joe Thompson at the University of Virginia’s Fabrication Facilities and Nanomaterials Characterization Laboratory.