Non-Beam Additive Manufacturing of Architected and Functional Cellular Materials

Abstract

Additive manufacturing has enabled the fabrication of cellular materials of previously unachievable complexity. Architected materials, including periodic lattices and stochastic foams, can now be designed to better satisfy predefined mechanical, thermal, and functional performance criteria. This work explores the fabrication and characterization of advanced architected composites using Fused Deposition Modeling (FDM). PLA-MXene composites were optimized, showing that 0.25 to 0.5 wt% MXene enhances stiffness, fracture strength, and energy absorption, while higher concentrations reduce performance. The study also investigates multi-material Triply Periodic Minimal Surface (TPMS) structures, combining brittle (PLA-graphene) and ductile (PLA-MAPP) polymers. Results indicate that 0.25 wt% graphene increases tensile strength by 18% and peak compressive stress by 30%, while MAPP improves ductility, increasing elongation at break by 15%. The addition of graphene and MAPP significantly improves the mechanical performance of TPMS structures, making them suitable for applications in aerospace, automotive, and biomedical fields. Additionally, Ni-TiO₂ metal matrix composites (MMCs) were fabricated using a novel process combining nitinol-rich filaments, 3D printing, and post-processing sintering. These MMCs exhibited a hardness of 258 HV and a compressive strength of 250 MPa, with thermal conductivity remaining stable up to 800°C, making them ideal for high-performance aerospace and defense applications. Finally, the EMI shielding capabilities of PVDF-graphene TPMS structures were examined. Neovius TPMS structures showed excellent shielding effectiveness, with a specific shielding effectiveness (SSE) of 94 dB cm³/g and absolute SSE of 62.5 dB cm²/g. The study also explored the impact of various design parameters on total shielding effectiveness (SET), demonstrating the potential for optimizing EMI shielding properties for advanced electronic systems.

Date of Award	9 May 2025
Original language	American English
Supervisor	Wael Zaki (Supervisor)