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201605 https://hdl.handle.net/2286/R.2.N.201605 http://rightsstatements.org/vocab/InC/1.0/ All Rights Reserved 2025 69 pages Masters Thesis Academic theses en Priyadarshi, Ayush Kang, Wonmo Nian, Qiong Razmi, Jafar Arizona State University Partial requirement for: M.S., Arizona State University, 2025 Field of study: Mechanical Engineering Auxetic structures, characterized by their negative Poisson's ratio, offer enhanced energy absorption capabilities, making them ideal for protective and impact-resistant applications. While their distinct geometries suit additive manufacturing, the influence of fabrication parameters on their mechanical performance remains underreported. This study addresses this gap by evaluating the mechanical behavior of 3D-printed auxetic structures, specifically Reentrant Honeycomb (REE), Arc Wall Unit Cells (AWUC), and their mass-optimized variants (OPT-REE and OPT-AWUC). Three polymeric materials—Thermoplastic Polyurethane (TPU), FlexiTough (a PLA blend), and Polypropylene (PP)—were selected for their varied mechanical characteristics and Fused Deposition Modeling (FDM) compatibility.Experimental results showed that TPU had low stiffness but near-complete elastic recovery, PP exhibited the highest stiffness and strength, and FlexiTough performed well near densification. While OPT-AWUC initially demonstrated lower mechanical performance, it ultimately outperformed others near densification. A preliminary analysis of printing parameters identified effects of layer thickness and raster orientations of 0° or 90° as key factors enhancing mechanical properties, especially in PP structures. This research provides insights into the interplay between geometry, materials, and printing parameters, offering guidelines for optimizing auxetic structures in protective applications. Mechanical Engineering Auxetic FDM Polymers Structural optimization Optimization and Mechanical Performance of 3D-Printed Auxetic Structures: Effects of Geometry, Material, and Printing Parameters