Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 7Citation - Scopus: 7A Comprehensive Study on Burst Pressure Performance of Aluminum Liner for Hydrogen Storage Vessels(ASME, 2021) Kangal, Serkan; Sayı, Abdülmecit Harun; Ayakdaş, Ozan; Kartav, Osman; Aydın, Levent; Artem, Hatice Seçil; Aktaş, Engin; Yücetürk, Kutay; Tanoğlu, Metin; Kandemir, Sinan; Beylergil, BertanThis paper presents a comparative study on the burst pressure performance of aluminum (Al) liner for type-III composite overwrapped pressure vessels (COPVs). In the analysis, the vessels were loaded with increasing internal pressure up to the burst pressure level. In the analytical part of the study, the burst pressure of the cylindrical part was predicted based on the modified von Mises, Tresca, and average shear stress criterion (ASSC). In the numerical analysis, a finite element (FE) model was established in order to predict the behavior of the vessel as a function of increasing internal pressure and determine the final burst. The Al pressure vessels made of Al-6061-T6 alloy with a capacity of 5 L were designed. The manufacturing of the metallic vessels was purchased from a metal forming company. The experimental study was conducted by pressurizing the Al vessels until the burst failure occurred. The radial and axial strain behaviors were monitored at various locations on the vessels during loading. The results obtained through analytical, numerical, and experimental work were compared. The average experimental burst pressure of the vessels was found to be 279 bar. The experimental strain data were compared with the results of the FE analysis. The results indicated that the FE analysis and ASSC-based elastoplastic analytical approaches yielded the best predictions which are within 2.2% of the experimental burst failure values. It was also found that the elastic analysis underestimated the burst failure results; however, it was effective for determining the critical regions over the vessel structure. The strain behavior of the vessels obtained through experimental investigations was well correlated with those predicted through FE analysis.Article Citation - WoS: 25Citation - Scopus: 39An Experimental Study on Friction Drilling of St12 Steel(Canadian Society for Mechanical Engineering, 2014) Kaya, Mehmet Tuncay; Aktaş, Alaattin; Beylergil, Bertan; Akyıldız, Hamza K.The aim of this study is to investigate the effects of drilling parameters such as friction angle, friction contact area ratio (FCAR), feed rate and spindle speed on workpiece surface temperature, thrust force and torque in friction drilling of ST12 material. The tool material is tungsten carbide coated with TiN treatment. Experimental results reveal that the thrust force and torque increases gradually with increasing friction angle, feed rate and FCAR. On the other hand, the thrust force and torque decreases with increasing drilling speed. It is found that drilling speed has an important effect on the workpiece surface temperature. As the drilling speed increases, the workpiece surface temperature increases. Increasing or decreasing the friction angle and FCAR has no significant effect on the workpiece surface temperature.Article Shear Strength of Pultruded Composite Pins With External Confinement(Taylor and Francis Ltd., 2014) Beylergil, Bertan; Aktaş, Alaattin; Pekbey, YelizWeight reduction using composites has gained increasing attention in recent times. In this study, pultruded composite pins (unconfined and confined) were manufactured and tested by using a custom double shear testing fixture. Different configurations were applied for confinement of the composite pins, including weft-knitted fabrics (plain, 1 × 1 rib, and Milano), woven fabrics and E-glass 130 tex fibers/adhesive cloth. They were externally wrapped and bonded to the unconfined composite pins. In each case, five identical specimens were tested, and shear strength data were analyzed by using two-parameter Weibull statistics. The results showed that the maximum shear strength took its highest value in the unconfined case for both average values of the test results and for 99% reliability under Weibull distribution. The confinement had a negative effect on the average shear strength of the unconfined pins. It was also seen that the 99% reliability values of shear strength were approximately equivalent to the 0.7 average value of the shear strength.Article Citation - WoS: 4Citation - Scopus: 4Enhancement of Flexural Performance of Wood Beams Using Textile Fabrics(Walter De Gruyter Gmbh, 2013) Beylergil, Bertan; Aktaş, Alaattin; Pekbey, YelizThe aim of this study was to investigate the flexural performance of wood beams (beech - Fagus orientalis Lipsky) reinforced with woven and selected weft knitted glass fabrics, namely, Milano and plain knit. Some physical and mechanical properties of the beech wood and the textile fabrics were determined in accordance with relevant ASTM standards. Twenty-four wood beams which have two different cross sections (I-shaped and square hollow) were manufactured and tested under a threepoint load. They were divided into two groups: Group A specimens were not reinforced to serve as a reference, whereas Group B specimens were reinforced with textile fabrics combined with adhesion. The flexural behavior of the specimens was studied through their load-deflection characteristics. The modes of failure were identified and categorized. The experimental results showed that the load-bearing capacity of reinforced beams increased significantly compared to the beam without reinforcement. This method can be used to repair and strengthen damaged wood beams.