ADDITIVE MANUFACTURING AND CHARACTERIZATION OF METAL PARTICLE INCORPORATED POLYMER MATRIX FUNCTIONALLY ENHANCED COMPOSITES

Date

2023-12-04

Author

UYAR, Özgür

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Increasing the structural capability of structures for various engineering applications while enhancing their functionality and reducing their weight by tailoring their internal morphology has always been a challenge for materials engineering. Advances in additive manufacturing (3D printing) methods have made it possible to tailor-design materials from micro to macro scale to fulfill these challenging property requirements. In this study, Fused Filament Fabrication (FFF) with metal powder incorporated polymer filaments has been used to process model structures with enhanced structural and functional capability. In this scope, the mechanical behavior of additively manufactured Triply Periodic Minimal Surface (TPMS) lattice structures such as Schwarz Primitive, IWP, and Neovius, which are commonly used lattice structures, has been investigated. FFF, being one of the most frequently used and feasible additive manufacturing techniques, was utilized to fabricate pristine polymer lattice structures with different relative densities of 30%, 40%, and 50% using Polylactic acid (PLA) and Polypropylene (PP) along with metal powder incorporated PP (metal/PP) composite lattice structures. The structural capability of the designed structures was determined by mechanically testing the additively manufactured polymeric structures. Moreover, finite element analyses have also been conducted, and their results were compared with the results obtained experimentally. It has been demonstrated that for developing and optimizing metal particle containing filaments for various applications, including additively manufactured lattice structures, particle morphology, aspect ratio, and volume fraction along with even particle distribution and dispersion throughout the filament, significantly impact the processing quality and final properties of the 3D-printed structures. It was generally concluded that incorporation of metal powder into PP (metal/PP) rendered it more processable for TPMS lattice structures compared to PLA (metal/PLA) filaments. However, despite the promising FEM results, the detachment issue in FFF printing hindered the ability of the composite filament with PP matrix (metal/PP) to meet the expected standards. Compressive test results revealed significant insights. Pristine PLA exhibited higher compressive strength than PP in a fully dense cubic (bulk) form. Reinforcement enhanced the properties of the PP matrix proportionally with additive content. However, PLA matrix reinforcement did not uniformly improve mechanical properties, possibly due to air gaps trapped between the layers. Higher relative density boosted compressive strength in TPMS structures, with detachment issues more pronounced in PP models. Metal particle addition unevenly affected strength in the case of PP and PLA matrices. Pristine filament manufacturability surpasses composites, impacting cube and TPMS fabrication. Increasing relative density enhanced strength in lattice structures. Notably, the IWP model exhibited superior compressive yield strength attributed to its effective stress distribution and self-supported structure.

Subject Keywords

Fused Filament Fabrication (FFF), Lattice Structure, Additively Manufactured Composites, Mechanical Testing, Relative Density

URI

https://hdl.handle.net/11511/107719

Collections

Graduate School of Natural and Applied Sciences, Thesis