2026/09/04
Multinozzle Architecture for Additive Manufacturing of High-Viscosity Thermosets for Aerospace Applications
Plante, R. (2026). Multinozzle Architecture for Additive Manufacturing of High-Viscosity Thermosets for Aerospace Applications. Thesis.
Over the past several years, additive manufacturing of polymers and composites has attracted growing interest for the production of lightweight, complex, and multifunctional structures. In aerospace applications, Direct Ink Writing (DIW) has emerged as a promising approach for fabricating architectured filament networks from viscous thermosetting materials, particularly for structured abradable coatings. However, the fabrication of such structures remains limited by the low build rates generally associated with fine-resolution DIW. Although solutions such as multinozzle systems have been proposed to increase throughput, the hydraulic resistance imposed by nozzle internal geometry remains comparatively underexplored. When the available extrusion pressure is limited, this resistance becomes a major process constraint. This project therefore focuses on the development, on the existing robotic additive manufacturing platform of the Laboratory of Multiscale Mechanics (LM2), of a tapered multinozzle architecture compatible with a practical pressure limit of 20 MPa. The objective is to replace the cylindrical multinozzle previously developed at the laboratory with a geometry better suited to the hydraulic constraints of the system. The proposed solution consists of a stereolithography-fabricated tapered multinozzle architecture comprising a 6 × 6 array of 36 outlets. To withstand the mechanical loads associated with high-pressure extrusion, the polymer component defining the flow is supported by a reusable metallic backing plate located outside the flow path. This separation of hydraulic and structural functions allows both the integration of a dense network of converging channels and rapid replacement of the ink-contacting component. Characterization of the printed printhead shows that SLA fabrication can produce outlets close to the nominal geometry, with measured mean diameters of 255.7 ± 14.1 µm for the nominal 230 µm design and 370.0 ± 22.5 µm for the nominal 350 µm design. The observations also revealed good outlet circularity and low internal channel roughness, with an average Ra of 0.50 ± 0.21 µm. These results confirm that SLA can be used to fabricate a fine-outlet multinozzle printhead with sufficient dimensional fidelity and surface quality for extrusion. The proposed architecture was then evaluated using three representative inks: a reference organic ink, an EPON 828-14%FS thermosetting ink, and an industrial EC3515-10%FS thermosetting composite ink. Relative to the cylindrical reference multinozzle, the tapered geometry reduced the required pressure by 71.6% for the organic ink and by 84.6% for the EPON 828-14%FS ink at an extrusion speed of 200 mm/s. For EC3515-10%FS, the fabrication of a periodic microscaffold was achieved at 100 mm/s at approximately 11 MPa using nominal 350 µm vii outlets, whereas comparable cylindrical configurations were not operable within the available pressure limit. Under these conditions, deposition through 36 outlets corresponds to a total flow rate greater than 500 mm³/s while still producing filaments below 500 µm in diameter. A representative microscaffold section consisting of 18 layers of 108 parallel filaments spaced 1 mm apart was fabricated in less than 3.5 minutes. The resulting microscaffold showed a mean surface deviation of +20.0 µm from the target geometry, and 85.6% of its surface points fell within a ±100 µm tolerance band. At a larger scale, analysis of a representative planar structure indicates that a 36-nozzle configuration could reduce the estimated fabrication time from 40.8 h with a single to 1.1 h at the same deposition speed, further highlighting the value of parallelization. Taken together, these results show that an SLA-fabricated tapered multinozzle architecture is a credible route for improving the hydraulic efficiency of Direct Ink Writing by substantially reducing the required pressure while increasing deposition rate. More broadly, this work illustrates how one additive manufacturing technology can be used to improve another, while contributing to the development of multinozzle DIW systems that are more accessible, more easily replaceable, and less demanding in terms of pressurization.