Sürdürülebilir Kalkınma Amaçları
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- MakaleAçık Erişim2026Scopus SJRQ4Comparative analysis of stress distributions and safety factor in tensile test specimens with different notch and hole geometries by finite element method
Korkmaz, Sümeyye Erdem; Gavgali, Esma
This study analyzes the effects of different notch and hole geometries (V-Notched, U-Notched, circular hole) on stress concentration in Ti-6Al-4V (Grade 5) Titanium alloy tensile specimens to provide optimized design recommendations for aerospace and biomedical applications. Finite element method (ANSYS Workbench) was employed to analyze three geometries under 15000 N static tensile loading. Von Mises stress distributions and stress concentration factors (Kt) were calculated and validated against Peterson and Neuber theoretical formulas with average error ±1.5%. Results revealed that V-Notched exhibited highest stress concentration (Kt = 5.78, σmax = 1156 MPa), while circular hole showed lowest (Kt = 2.25, σmax = 454.12 MPa). U-Notched demonstrated intermediate performance (Kt = 2.84, σmax = 995.45 MPa). Increasing notch root radius from 0.5 mm to 2.0 mm achieved 51% reduction in stress concentration factor. Maximum shear stress values were 232.74 MPa, 506.38 MPa, and 640 MPa for circular, U-Notched, and V-Notched respectively, while maximum normal stress values reached 467.06 MPa, 1015.1 MPa, and 1809 MPa. Safety factor analysis showed that circular hole configuration meets aerospace standards (FS = 2.05 > 1.5), while U-Notched (FS = 0.93) and V-Notched (FS = 0.80) fall below minimum safety criteria. U-Notched exhibited highest total displacement (1.210 mm), indicating compliance effects. For aerospace and biomedical applications, circular holes should be preferred over sharp notches (154% stress reduction), and minimum corner radius ≥2.0 mm is recommended. The critical finding that geometric optimization provides 2.6× safety improvement without material changes demonstrates the powerful role of design in structural reliability for weight-critical applications.
- MakaleAçık Erişim2022Investigation of ball milling effect on superconducting properties of oleic acid added bulk MgB2 superconductors produced by two different methods; [İki farklı metot ile üretilen oleik asit katkılı külçe MgB2 süperiletkenlerin süperiletkenlik özellikleri üzerine bilyeli öğütme etkisinin araştırılması]
Erdem, Özge
The effect of ball milling on the microstructure and some superconducting parameters such as flux pinning force (Fp) and critical current density (Jc) of the oleic acid (C18H34O2) added MgB2 bulk samples produced by two different methods, was analysed in this article. In the first method, ball milling was applied to the samples produced by using boron (B) powders coated with carbon (C) released from oleic acid. In the second method, oleic acid was mixed with magnesium (Mg) and B powders at the same time and then the same ball milling process used in the first method was applied to the powder mixture. The structural, magnetic and electrical properties of the produced samples were analysed. The results showed that ball milling process enhances the homogeneity of the structure, decreases the grain size and improves the grain connectivity of MgB2. Also, C substitution into MgB2 lattice resulting in an increase in electron scattering and disorders, enhances after ball milling process. It supplies a significant increase in Jc at high fields and causes a slightly decrease in transition temperature (Tc), especially for the samples produced by using the first method. Because the first method supports the ball milling effect on the homogenous dispersion of oleic acid addition in the MgB2 structure and the C entrance to MgB2 lattice, acting as pinning centres, the best Jc and Fp values at high fields was obtained for the produced samples with second method.
AtıfScopus3OpenAlex1
İncele - MakaleAçık Erişim2021Potential bacteriocinogenic lactic acid bacteria from pastırma; [Pastırmadaki potansiyel bakteriyosinojenik laktik asit bakterileri]
Güllüce, Medine; Kaya, Mükerrem; Kaban, Güzin; Karadayi, Mehmet; Alaylar, Burak; Kamiloğlu, Aybike; Işik, Ceyda; Fettahoğlu, Kübra
Recent researches conducted have focused on the possibility of using bacteriocin produced by lactic acid bacteria both (LAB) as protective cultures and as natural antimicrobial agents in dry cured meat products such as pastırma. In the present study, 50 lactic acid bacteria strains, previously isolated from various traditional pastırma samples, were tested for their antimicrobial potentials. Determination of antagonistic activities against food-borne pathogenic strains (Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus) were done by using agar-spot and well diffusion assays. Then, active isolates were identified by using 16S rRNA gene sequence analysis. According to the results, 11 of tested LAB were determined with significant bacteriocinogenic potential and these were assigned to as 1 Lactobacillus plantarum, 9 L. plantarum subsp. plantarum and 1 Pediococcus pentosaceus. In conclusion, it was reached that the isolated/identified bacteriocin-producing lactic acid bacteria strains from pastırma samples have a significant potential to prepare pure or crude bacteriocin preparations.
AtıfScopus1OpenAlex1İncele - DergiGumushane Universitesi Fen Bilimleri Dergisi