Person: BAYRAM, ALİ
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BAYRAM
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ALİ
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Publication AISI 1050 çeliği üzerine inconel 718 lazer dolgu kaynağının morfolojisi, mikroyapısı ve mekanik karakterizasyonu(Bursa Uludağ Üniversitesi, 2023-05-08) Arı, Ali; Karagöz, Taner; Arslan, Orhun; Bayram, Ali; BAYRAM, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü; 0000-0001-7311-8358Bu çalışma kapsamında, Inconel 718 tozunun AISI 1050 imalat çeliği üzerine lazerle dolgu kaynağı işlemi uygulandı. Bu işlem sırasında, dispersiyonun mekanik özellikler üzerindeki etkisini analiz etmek için, ilgili parametrelerde üretilen numuneler üzerinde ampirik bir çalışma gerçekleştirildi. Sonuçlar, kopma gerilmesi ve süneklik için yüksek sapmalar olduğunu göstermektedir. Bu dağılım, biriken malzemede gözenekliliğin varlığından kaynaklanmaktadır. Ayrıca, en iyi sonuçlar merkez bölgedeki numunelerden alınırken, dış bölgelerden alınan numuneler üzerinde yapılan testler kopma gerilmesi ve süneklik için daha düşük değerler göstermiştir. Bunun yanında sertlik değerleri incelendiğinde ısıdan etkilenen bölgenin ana malzemeden daha sert olduğu ve bu da ısıdan etkilenen bölgenin soğuma hızından kaynaklandığı görülmüştür. Buna ilaveten de Laves fazı, zamanla kırılmaya yol açan mikro boşlukların üretilmesinin ana nedeni olduğu anlaşılmıştır.Publication Springback/springforward behaviour of dp steels used in the automotive industry(Univ Osijek, Tech Fac, 2020-01-01) Umur, Yeliz; UMUR, YELİZ; Aydin, Hakan; AYDIN, HAKAN; Yiğit, Kurtulus; YİĞİT, KURTULUŞ; Bayram, Ali; BAYRAM, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; 0000-0001-7364-6281; AAK-4598-2021The springback/springforward behaviour in a V-die/punch of DP600 and DP780 steels used in the automotive industry was investigated. For this study, experiments were carried out by using different combinations of parameters, including material thickness, die/punch radius, bending angle and rolling direction and the resulting measurements showed that the DP780 steel consistently exhibited greater springback values than the DP600. Augmentation of the rolling direction at an angle from 0 degrees to 90 degrees and punch radius inhibited springback formation and hastened springforward, particularly for small bending angles. The springback angle decreased with increasing material thickness and curvature radius, and increased with the bending angle, particularly for the punch tip radius of 2 mm. Increasing the ratio of curvature radius to material thickness (rt(-1)) also caused the springback to decline. In addition, a new dimensionless parameter was developed and the critical value for calculating the transition from springback to springforward was determined.Publication The electroless monolayer and duplex ni-b and ni-p coatings for 316l stainless steel in synergistic combination of mechanical (wear) and chemical (corrosion) processes(Wiley-v C H Verlag Gmbh, 2023-03-17) Mindivan, Ferda; Mindivan, Harun; Bayram, Ali; BAYRAM, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.Conventional processes are performed to improve the low hardness and low wear resistance properties of 316L steel, but these processes generally decrease the corrosion resistance. Electroless nickel alloy coatings provide a hard, wear-resistant, and corrosion-resistant surface. Thus, the present study aims to investigate the wear, corrosion, and tribocorrosion behaviors of monolayer and duplex coatings with nickel-boron (Ni-B) and nickel-phospore (Ni-P) on 316L steel in comparison with 316L steel in dry sliding and 0.9 wt% NaCl solution environments. It is determined that the coatings have a mixture of crystal and amorphous structures, the interfaces on the 316L are uniform, and the compatibility between the layers is good. The Ni-B, Ni-P/Ni-B, and Ni-B/Ni-P coatings are 2.3, 2.06, and 1.6 times as hard as the 316L, respectively. The wear rates of Ni-B, Ni-P/Ni-B, and Ni-B/Ni-P coatings show decrease by 99.3%, 92.5%, and 99.1% in the dry-sliding condition and by 98.5%, 30.1%, and 19.1% in the tribocorrosion condition compared with that of 316L, respectively. It is observed that the monolayer Ni-B coating exhibits superior hardness, a higher contact angle, low electrical conductivity, and better tribological performance in both dry sliding and tribocorrosion conditions compared to the 316L and duplex coatings.Publication Single track geometry prediction of laser metal deposited 316l-si via multi-physics modelling and regression analysis with experimental validation(Korean Inst Metals Materials, 2022-06-11) Müslim, Talha; Özalp, A. Alper; ÖZALP, ABDURRAHMAN ALPER; Bıyıklı, Merve; BAYRAM, ALİ; Karagöz, Taner; Calli, Metin; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Otomotiv Mühendisliği Bölümü.; 0000-0002-4148-3163; 0000-0002-4976-9027Laser metal deposition (LMD) is an additive manufacturing process used in manufacturing freeform geometries, repair applications, coating and surface modification, fabrication of functionally graded materials. It has a broad range of applications in various industries, including aviation, space, defence, automotive, tooling, etc. In this work, a multi-physics model of the LMD process was developed to rapidly predict the geometrical characteristics of the single clad track using the commercial software package Flow-3D. The volume of fluid (VOF) method was integrated to differentiate the interface between the metallic and gaseous cells. To validate the numerical model single bead tracks were deposited, and cross-sections of the beads were analysed. Mathematical formulae to predict different aspects of the single clad track (height, width, and depth) were derived using regression analysis. The influence of the process parameters on the geometrical characteristics of the single clad track was analysed in detail using analysis of variance (ANOVA). Both multi-physics model and mathematical regression model results were compared to the experimental measurements. The results were in good agreement with the experimental results.Publication Comparison of the mechanical properties of chopped glass, carbon, and aramid fiber reinforced polypropylene(Sage Publications, 2022-05-01) Arı, Ali; Bayram, Ali; Karahan, Mehmet; Karagöz, Secgin; BAYRAM, ALİ; KARAHAN, MEHMET; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü; Bursa Uludağ Üniversitesi/Meslek Yüksekokulu/Tekstil Bölümü; 0000-0003-3915-5598; AAK-4298-2021; GZC-1297-2022In this work, a comparative assessment of the mechanical properties of chopped glass-carbon-aramid fiber reinforced polypropylene (PP) composites was carried out. Reinforcement and matrix materials were mixed with the extrusion method, and then composite materials were produced in the form of plates with the press molding technique. The composites' tensile, 3-point bending, and drop weight tests were carried out and the surface morphology of the fractured surfaces was examined by Scanning Electron Microscope (SEM). The tests' results indicate that the mechanical properties increase significantly in the presence of fiber. On the other hand, it is observed that the effect in percentage decreases as the fiber content increases. Moreover, It was observed that some of the fiber materials were pulled out from the matrix as a result of stress. ANOVA analysis using S/N values, and F-Test were performed to observe the effectiveness of each test factor (fiber type, and fiber additive content) on the test results. Finally, an optimization study was carried out to obtain the mathematical expression by fitting the experimental data.Publication The optimisation of welding parameters for electrical resistance spot-welded twip steels using a taguchi method(Pamukkale Üniversitesi, 2018-01-01) Tutar, Mümin; Aydın, Hakan; Bayram, Ali; TUTAR, MÜMİN; AYDIN, HAKAN; BAYRAM, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü; 0000-0002-7286-3433; 0000-0001-7364-6281; J-2753-2016; JQB-9181-2023; GZC-1297-2022The aim of this work is to optimize the welding parameters of electrical resistance spot welded TWIP steel sheets using a Taguchi method. The welding parameters, such as weld current, welding time and electrode force, were determined according to the Taguchi orthogonal array L9 using a randomized approach. The optimum welding parameters for the peak tensile shear load of the joints were predicted, and the individual importance of each parameter on the tensile shear load of the resistance spot weld was evaluated by examining the signal-to-noise (S/N) ratio and analysis of variance (ANOVA). The optimum weld current, welding time and electrode force were found to be 12 kA, 300 ms and 3000 N, respectively. The ANOVA results indicated that the weld current has the highest statistical effect with 78.73% on the tensile shear load, followed by the welding time and electrode force. The tensile shear load of the resistance spot welding joints increased with increasing weld current and electrode force. But, higher welding time led to relatively lower tensile shear load. In addition, the fracture surface characterization of the selected joints was conducted using scanning electron microscopy (SEM) technique. In this examination, it has been found that the joints having higher weld strength exhibited a relatively more ductile fracture characteristic.Publication Comparative evaluation of mechanical properties of short aramid fiber on thermoplastic polymers(Sciendo, 2023-03-01) Arı, Ali; Arslan, Orhun; Bayram, Ali; BAYRAM, ALİ; Karahan, Mehmet; KARAHAN, MEHMET; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü.; Bursa Uludağ Üniversitesi/Eğitim Fakültesi.; AAA-3643-2019 ; AAK-4298-2021This study investigated the mechanical performance of short aramid fiber on polypropylene, polyethylene, polyamide 6, and polyamide 12. Extrusion, press molding, and CNC cutting methods were used in the production of composite samples. Tensile, three-point bending, drop weight and hardness tests of the composites were carried out. As the fiber volume fractions increased, the mechanical properties of the composites improved, but the most efficient fiber fractions for each matrix changed. To analyze the performance of the fibers in the matrix on the composites, scanning electron microscope (SEM) images of the fractured surfaces as a result of tensile and drop weight tests were examined. As the fiber volume fractions increased, the fiber deformation increased, and as a result, the mechanical performance of the composites was adversely affected. Analysis of variance (ANOVA) and F test were performed using signal/noise values to analyze in detail the effect of experimental parameters on output values. Finally, the results of a regression equation model were compared with the experimental readings. It was found to be in good agreement with the model and the results of the experiment.