Nikiel, Piotr
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Item type:Article, Access status: Open Access , Influence of structural characteristics on the mechanical properties of FDM printed PLA material(AGH University of Science and Technology Press, 2020) Szczepanik, Stefan; Nikiel, PiotrThe present study reports on the influence of printing process parameters, architecture, raster, infill orientation and filling on the density, macrostructure, and mechanical properties, including impact resistance, of biodegradable polymer parts fabricated in polylactide (PLA) on a desktop printer. It complements and considers phenomenologically the results of recently published similar studies, including the use of recycled filament. In our study, complex mechanical properties for the samples printed at the same time on a Replicator 2 printer were investigated. Three samples were printed for each test. Full mechanical characteristics (tensile, compression and bend strengths and impact resistance) of the printed PLA material are reported. This is the novelty in comparison to other studies, where the samples test were printed individually or in a series for each test. The shape and thickness of the layered macrostructure, the presence of holes inside the layers, the number of shell perimeters and the fill density all influenced the tensile properties of the printed materials. These results show the possibility of printing with a 0.3, i.e. shorter printing time than 0.1, 0.15 and 0.18 mm layer thicknesses also reported, without significant decrease in mechanical properties. It is interesting to note that the compressive strengths, the yield of 70-80 MPa and a UTS 113-120 MPa for the printed material with a fill density of 94-96% are comparable with those of aluminum.Item type:Article, Access status: Open Access , AA2024/fly ash lightweight composites fabricated by powder metallurgy(2024) Nikiel, PiotrThe paper presents the experimental results on the fabrication of lightweight aluminum alloy AA2024 matrix composites reinforced with fly ash microspheres using powder metallurgy (PM) via hot pressing. The primary aim was to achieve a composite with the highest possible matrix density while preserving undamaged microspheres. A mixture of powders consisting of AA2024 alloy powder and 10 wt% fly ash was pressed at 550°C and pressures of 5, 10, 20, and 30 MPa for two minutes. The obtained composites had densities in the range of 1.93 - 2.31 g/cm3. Microstructural analysis revealed uniform distribution of the fly ash microspheres in the aluminum alloy matrix. The hardness of the composites was comparable only between the samples pressed at 10, 20, and 30 MPa, falling within the range of 118 to 122 HV0.1. The sample pressed at 5 MPa exhibited significantly lower hardness of 98.8 HV0.1. The composites produced by pressing at 20 and 30 MPa were characterized by high yield strength and compression strength, ranging from 211 to 216 MPa and 300 to 354 MPa, respectively. The composites pressed applying lower pressures, especially those at 5 MPa, exhibited significantly lower values of plastic yield strength and compression strength, with values of 109 MPa and 115 MPa, respectively. Taking into account the density, the number of damaged microspheres, and the microstructure of the AA2024/fly ash composite, the optimal pressing range is between 10 - 20 MPa, but superior mechanical properties were achieved after pressing at 20 and 30 MPa.