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3. Development and performance evaluation of epoxy-based hybrid composites for sustainable personal protective equipment in automotive applicationS. Dinesh, S. Balasubramani, A. R. Pradeepkumar, D. Nandhakumar, V. Hariharan, R. Sendil Kumar, 2025, izvirni znanstveni članek Ključne besede: hybrid composite, hand lay-up method, mechanical properties, personal protective equipment
Objavljeno v DiRROS: 24.04.2025; Ogledov: 108; Prenosov: 41
 Celotno besedilo (1,07 MB)
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4. Comparison of powder-bed fusion, directed-energy deposition and hybrid additive manufacturing of Ti6Al4V components: microstructure, corrosion and mechanical propertiesAleksandra Kocijan, Simon Malej, 2025, izvirni znanstveni članek Ključne besede: additive manufacturing, Ti6Al4V, microstructure, corrosion, mechanical properties
Objavljeno v DiRROS: 10.04.2025; Ogledov: 118; Prenosov: 72
Celotno besedilo (4,71 MB)
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5. Research on the water-holding capacity and mechanical properties of backfill based on a damage-softening constitutive model: effects of different permeability forcesChaoyi Yang, Zhenggao Huang, Wenzhong Sha, Heng Huang, Rugao Gao, 2025, izvirni znanstveni članek Ključne besede: backfill, centrifugal simulation, osmotic pressure, mechanical properties
Objavljeno v DiRROS: 21.02.2025; Ogledov: 202; Prenosov: 93
Celotno besedilo (5,71 MB)
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6. AISI H13 tool steel - comparison between powder bed fused and classically produced partsSamo Tome, Irena Paulin, Matjaž Godec, 2024, objavljeni znanstveni prispevek na konferenci Povzetek: AISI H13 Is very commonly used in the hot-work category of steels. Whether it is used as a forging die, a hotcutting tool, or a mold in injection molding or die casting, it is always on the table, as the material of choice. However, its potential has not yet been fully realized. New manufacturing techniques such as additive manufacturing (AM) broaden the horizon of the material’s application, and promise improved performance, through optimized geometry, unobtainable by traditional means, and heightened mechanical properties. One of the more widespread AM processes is Powder Bed Fusion (PBF) where a laser or electron beam constructs the model, by meting a thin coating of metal powder applied to a base plate. By repeatedly applying and melting powder, the end result is a layer-by-layer produced part. However, the techniques for producing such parts are not yet refined enough and require further research. Problems like porosities, part deflection, and crack formation due to residual stress are commonplace, while comparably low mechanical properties in the asprocessed state call for post-production treatments. Naturally, every technique has its boons and drawbacks, and that is what this work aims to analyze - How do the PBF parts compare to classically produced ones, and what are the difficulties in producing the later-mentioned parts.
Ključne besede: powder bed fusion, tool steel, additive manufacturing, mechanical properties
Objavljeno v DiRROS: 16.01.2025; Ogledov: 292; Prenosov: 139
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7. Investigating the synergistic impact of freeze-thaw cycles and deicing salts on the properties of cementitious composites incorporating natural fibers and fly ashIldikó Merta, Vesna Zalar Serjun, Alenka Mauko Pranjić, Aljoša Šajna, Mateja Štefančič, Bojan Poletanovic, Farshad Ameri, Ana Mladenović, 2025, izvirni znanstveni članek Povzetek: In cold climates, concrete structures confront durability challenges due to harsh conditions. This study evaluates the effects of incorporating natural fibers, such as hemp and flax fibers (at 1 vol%), and partially replacing cement with fly ash (at 25 and 50 wt%) on the properties of cementitious composites subjected to accelerated aging under freeze-thaw cycles and deicing salts. Findings reveal that natural fibers enhance the freeze-thaw resistance, reducing deterioration (scaling) to 5-8% after 56 cycles. When mortars were subjected to accelerated freeze-thaw cycles, the compressive strength of plain mortar significantly decreased (up to 57%). However, adding natural fibers to the matrix substantially reduced its compressive strength loss. In the case of flexural strength, plain mortars experienced 33% loss, while hemp, flax, and polypropylene fiber mortars showed only 13%, 23%, and 10% losses, respectively. Furthermore, mortars experience a notable enhancement in their energy absorption capacity when reinforced with natural fibers, particularly with hemp fibers (up to 348% higher than plain mortar). Under harsh conditions, hemp and flax-reinforced mortars, with 25wt% fly ash replacement, lose the compressive strength significantly however still demonstrate an alternative to synthetic fibers in terms of flexural strength. Even with 25wt% of fly ash, mortars with natural fiber reinforcement display significantly superior energy absorption capacities compared to plain mortars (up to 48%).
Ključne besede: cementitious composites, natural fibers, freeze-thaw cycles, mechanical properties, mass loss, fly ash
Objavljeno v DiRROS: 23.12.2024; Ogledov: 444; Prenosov: 156
Celotno besedilo (10,99 MB)
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8. Laser powder bed fusion parameters optimization for enhanced mechanical properties of EOS Co-Cr dental alloyDalibor Viderščak, Zdravko Schauperl, Biserka Runje, Sanja Šolić, Amir Ćatić, Matjaž Godec, Irena Paulin, Črtomir Donik, 2024, izvirni znanstveni članek Povzetek: This research explores how variations in laser powder bed fusion (LPBF) parameters—laser power (P), scanning speed (v), and base plate preheating temperature (ϑp)—affect the mechanical properties of the EOS Co-Cr SP2 dental alloy. A central composite design (CCD) was used to optimize the process parameters. Mechanical testing focused on crucial properties for dental applications, including yield strength (Rp0.2), elongation (ε), toughness (KVa), and flexural strength (Rms). Microstructural analysis was conducted using light and electron microscopy, while XRD identified microstructural phases. Statistical analysis (ANOVA, Scheffé post hoc test, α = 0.05) revealed significant effects of P, v, and ϑp on the mechanical properties. Response surface models (RSMs) were developed, and optimal parameters were determined to achieve maximum toughness and flexural strength. Maximum values were obtained with laser power above 205Wand base plate preheating at 310 ◦C. The mathematical model predicted toughness values with less than 5% deviation from experimental results, indicating high accuracy.
Ključne besede: LPBF, production parameters, Co-Cr dental alloy, CCD, mechanical properties, ANOVA
Objavljeno v DiRROS: 18.10.2024; Ogledov: 408; Prenosov: 8267
Celotno besedilo (8,69 MB)
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9. Effect of Ti and S content on the properties and machinability of low-carbon ferritic–pearlitic steelBoštjan Arh, Franc Tehovnik, Franci Vode, Bojan Podgornik, 2024, izvirni znanstveni članek Povzetek: This research was focused on the effect of Ti and S content on the formation of non-metallic inclusions and their influence on the mechanical properties and machinability of low-carbon ferritic– pearlitic steels. An analysis and classification of the non-metallic inclusions were carried out. The tensile strength and impact toughness were determined from samples taken in the rolling direction. Machinability investigations were carried out on a CNC turning machine and by analyzing the surface roughness. TiO-TiN inclusions are present in steels with an increased Ti content. In these steels, the hardness, tensile strength, and cutting forces increase with a higher proportion of Ti. In the second group of steels with increased contents of S, Al, and Ca, MnS and CaO-Al2O3-MnS non-metallic inclusions are formed. As the S content increases, the tensile strength and cutting forces decrease, while the impact toughness increases. In steels with added Ti, the This research was focused on the effect of Ti and S content on the formation of non-metallic inclusions and their influence on the mechanical properties and machinability of low-carbon ferritic– pearlitic steels. An analysis and classification of the non-metallic inclusions were carried out. The tensile strength and impact toughness were determined from samples taken in the rolling direction. Machinability investigations were carried out on a CNC turning machine and by analyzing the surface roughness. TiO-TiN inclusions are present in steels with an increased Ti content. In these steels, the hardness, tensile strength, and cutting forces increase with a higher proportion of Ti. In the second group of steels with increased contents of S, Al, and Ca, MnS and CaO-Al2O3-MnS non-metallic inclusions are formed. As the S content increases, the tensile strength and cutting forces decrease, while the impact toughness increases. In steels with added Ti, the machining is more difficult, but a finer surface is achieved after turning, while a higher S content results in an increased fraction of softer sulfide inclusions, which reduce the cutting forces but also result in a reduced surface quality. turning, while a higher S content results in an increased fraction of softer sulfide inclusions, which reduce the cutting forces but also result in a reduced surface quality.
Ključne besede: non-metallic inclusions, mechanical properties, machinability, surface roughness
Objavljeno v DiRROS: 03.09.2024; Ogledov: 504; Prenosov: 565
Celotno besedilo (12,95 MB)
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10. An evaluation of marine sediments in terms of their usability in the brick industry : case study Port of KoperPatrik Baksa, Franka Cepak, Rebeka Kovačič Lukman, Vilma Ducman, 2018, izvirni znanstveni članek Povzetek: A dredging process is essential for the development of harbours and ports, allowing the functional daily operation of the port. The management of dredged material represents a worldwide challenge, especially considering unwanted deposition of material. Because of their chemical, petrographic, mineralogical and homogeneity composition, marine sediments could represent an appropriate raw material for the brick industry, particularly for the production of clay blocks, roofing and ceramic tiles. In this study dredged material from Port of Koper was tested for such use, thus various analyses were carried out in order to determine if the dredged material is environmentally friendly and suitable for use in the brick industry. These included: chemical analysis, mineralogical analysis, particle size analysis, chloride content analysis and tests of firing in a gradient furnace. Furthermore, tests of mechanical properties, as well as tests of the frost-resistance of the samples were carried out. On the basis of the primary analyses and samples prepared in a laboratory, it was confirmed that marine sediments from the Port of Koper, without any additives are only conditionally suitable as a source material for producing brick products, because without additives they exhibit too much shrinkage on drying and firing, as well as high water absorption, this can be improved by the incorporation of suitable additives, for example, virgin clay or other suitable waste material. The approach described herewith can also be followed to assess sediments from other ports and rivers regarding its potential use in clay brick sector.
Ključne besede: dredge marine sediment, recycling, clay bricks, mechanical properties, chemical analysis
Objavljeno v DiRROS: 14.08.2024; Ogledov: 559; Prenosov: 304
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