Yazar "Avcu, Adem" seçeneğine göre listele

Listeleniyor 1 - 7 / 7
  • [ X ]
    Öğe
    A Finite Element Method Study of Polymer Exchange MembraneFuel Cell End Plate Materials by Using Arcan Specimen
    (2021) Avcu, Adem; Tüccar, Gökhan; Choupan, Naghdali
    In the current days, fuel cells are more preferred to generate electricity due to their positive sides. Because, if they use hydrogen andoxygen as fuel, they only produce electricity, heat, and water. This property of fuel cells is significant because it preventsenvironmental and chemical pollution, therefore, they contribute positively to the environment. In addition, they have more positiveaspects such as having no moving or rotating parts. Therefore, they don’t require mechanical maintenance and don’t make noise.Besides, they can be used in a wide range of areas as mobile and stationary power sources for electricity generation. There are manyfuel cell types but proton exchange membrane fuel cell (PEMFC) is more common than the other fuel cell types. It consists of partssuch as an endplate, bipolar flow plate, gas diffusion layer, catalyst layer, and membrane. End plates are located on the outer side ofPEMFC and hold together its stacks. In the design of the endplates, the state of fracture energy should be considered in differentloading conditions. Because the material may fail if it is designed only for the strength of materials concepts. In this paper, pure modeI, pure mode II and mixed mode fracture energy behavior of different materials were investigated numerically by using Arcanspecimen.
  • [ X ]
    Öğe
    A Numerical Investigation of The Fracture Energy of Materials for Fuel Cell End Plates
    (2021) Avcu, Adem; Choupan, Naghdali; Tüccar, Gökhan
    Nowadays, with increasing energy requirements, the use of clean energy resources has become important. Fuelcells are an important key for clean energy technology due to wide range of utilization areas such as automotive,portable power applications, electricity generation, space, aviation and naval technologies. Additionally, theyhave many significant properties such as not producing harmful gases, therefore they do not cause environmental and chemical pollution. Besides, they have not any moving parts, also they do not produce noise. Bycomparison to fossil fuel, fuel cells have high efficiency that reaches up to 60% in appropriate conditions. ProtonExchange Membrane Fuel Cell (PEMFC) has many advantages than other fuel cell types due to simple structure,higher efficiency and low operating temperature. PEMFC may consist of one or more stacks to generate moreelectricity. End plate of PEMFC holds together all parts of it. Therefore, the material selection for end plate isimportant to provide safe conditions. To use PEMFC safely, investigation of material fracture energy is requiredto decide that the material is in safe conditions or not. There are three fracture energy modes which are mode I,mode II and mode III. There are many methods to investigate failure of material at different modes. Unlike othermethods, Arcan specimen gives facility to evaluate of mode I, mode II and mixed modes. The main purpose ofthis paper was to compare the results of fracture energy (stain energy release rate) of different materials for endplates in fuel cells. Another goal was to select a suitable material was selected as PEMFC end plate.
  • [ X ]
    Öğe
    Assessing the safety and reliability of type-3 high-pressure composite tanks: a comprehensive analysis of failure metrics
    (Springer India, 2024) Avcu, Adem; Seyedzavvar, Mirsadegh; Boga, Cem; Choupani, Naghdali
    Pressure tanks play a pivotal role in various industrial applications, serving as vessels for the storage of gases under different pressures and environmental conditions. The burgeoning interest in hydrogen gas as a clean energy source has necessitated a comprehensive assessment of pressure tank structural integrity, particularly under high-pressure demands exceeding 700 bar. In this study, we systematically investigate the influence of different aluminum alloys, including AL6061, AL7075, and AL7178, reinforced with various fiber/epoxy composite materials. Our primary objective is to identify the optimal combination of liner and composite materials, along with the number of composite layers and fiber winding orientations that minimize distortion energy within the tank's liner and composite layers while maximizing safety factors. Our results indicate that distortion energy decreases as the fiber angle increases from zero to 75 degrees, with the ideal fiber orientation angle shifting with the number of composite layers. The lowest distortion energy levels in the liner were achieved in composite tanks comprising 60 laminates of reinforcing composite material, wound at an orientation angle of [+/- 55 degrees/90 degrees]. Across various internal pressure levels, pressure tanks reinforced with boron/epoxy composite material consistently outperformed other fiber materials. In terms of aluminum liner materials, AL6061 exhibited a remarkable 10.5% reduction in distortion energy on average when compared to AL7075. Safety indices revealed that pressure tanks reinforced with aramid/epoxy composite material provided the highest level of reliability, particularly when applying the maximum principal stress criterion. Carbon/epoxy and graphite/epoxy composites followed closely. In contrast, glass/epoxy and Kevlar/epoxy composites did not meet the stringent safety requirements for high-pressure storage tanks. These findings offer invaluable guidance for designing high-pressure composite tanks, ensuring their structural integrity and safety when storing hydrogen gas at elevated pressures, and exemplify the importance of materials and design considerations for such critical applications.
  • [ X ]
    Öğe
    Characterizing the effects of liner and fiber-reinforced resin composite shell on fracture energy in type-III high-pressure composite tanks
    (Springer Heidelberg, 2024) Avcu, Adem; Seyedzavvar, Mirsadegh; Boga, Cem; Choupani, Naghdali
    The increasing adoption of fuel-cell vehicles, driven by their environmentally friendly zero-emission features, is a crucial step towards reducing environmental damage. However, current research primarily focuses on stress-related aspects of pressurized tanks, leaving a critical knowledge gap regarding potential fractures within the tank's body, which can accelerate pressure tank failure. This study aims to address this concern by analyzing alternative fiber materials beyond carbon fiber in a finite element analysis model, with the primary objective of enhancing the durability of pressurized tanks for hydrogen-fueled vehicles against fracture loading. The investigation revolves around the fracture behavior of type-III high-pressure composite tanks, pivotal components for the secure operation of hydrogen-powered fuel cell vehicles. Various configurations of Al6061 and Al7178 liners coupled with six distinct fiber materials and six different winding orientations [(+/- 15/90)n]T, (+/- 30/90)n, [(+/- 45/90)n]T, [(+/- 55/90)n]T, [(+/- 60/90)n]T, and [(+/- 75/90)n]T have been meticulously assessed to provide an in-depth analysis of fracture energy behavior in composite tanks. The stress intensity factor (GI) was computed using a compact tension model developed in Abaqus, for all composite variations under consistent conditions, providing a robust foundation for understanding the fracture behavior. Additionally, MATLAB was utilized to calculate the effective elastic modulus for the selected composite materials. Subsequently, the strain energy release rate was derived from the relationship between the GI and the effective elastic modulus of composite tanks. The derived GI revealed notable improvements in fracture resistance for specific composite shells and liner materials, particularly at higher winding orientations. The results emphasized the superior performance of boron-epoxy composite shells for type-III pressure vessels, exhibiting the lowest GI values and exceptional crack resistance. Notably, Al7178 combined with boron-epoxy outperformed Al6061 composites at higher winding orientations, while glass-epoxy shells exhibited greater susceptibility to crack propagation, especially in specific ply orientations.
  • [ X ]
    Öğe
    Fracture analysis of materials used in high pressure hydrogen storage tanks
    (Adana Alparslan Türkeş Bilim ve Teknoloji Üniversitesi, 2024) Avcu, Adem; Boğa, Cem; Seyedzavvar, Mırsadegh
    Bu çalışma, tip III kompozit basınç tankının kırılma tokluğunun belirlenmesine odaklanmıştır. Bu amaçla tip III kompozit basınçlı tanktan alınan numuneler üzerinde belirtilen yöntemlere uygun olarak deneysel ve sayısal çalışmalar yapılmıştır. Bu çalışmanın temel amacı klasik dayanım yaklaşımına ek olarak boru veya basınçlı tank gibi dairesel şekilli malzemelerin kırılma tokluğunun doğru bir şekilde belirlenmesidir. Bu amaçla, tankın çember çekme mukavemeti ve kırılma tokluğunu belirlemek için üniversal test makinesinde kullanılmak üzere fikstürler üretildi. Daha sonra basınç tankından alınan numuneler ile bölünmüş disk çekme aparatı (split disk tensile test – SDT) kullanılarak çekme testleri yapılmıştır. Tankın çekme mukavemeti belirlendikten sonra elastisite modülü de belirlenmiştir. Ayrıca tank gövdesi Abaqus ile sonlu elemanlar yöntemi kullanılarak düz plaka olarak modellenmiş ve deneysel sonuçlarla karşılaştırıldığında elastisite modülü %98,34 doğrulukla tahmin edilmiştir. Çekme testinin ardından tankın kırılma tokluğunu belirlemek için kavisli CT (comapckt tension) numuneleri kullanılarak deneysel çalışmalar yapıldı ve deneysel sonuçlar düz olarak modellenmiş CT sayısal modeliyle karşılaştırıldı. Deneysel ve sayısal mod I gerilme yoğunluk faktörü değerlerinin %2,7 sapma ile birbirine yakın elde edilmiştir. Son olarak PRNB (pipe ring notched bending) yöntemi ile deneysel ve sayısal çalışmalar yapılmıştır. Bu yöntemin sayısal modeli kullanılarak basınç tankının kırılma tokluğu hesaplanmıştır. Bu model aynı zamanda mod I kritik gerilme yoğunluk faktörüne odaklanarak, çatlak uzunluğunun değişiminin tankın depolama basıncı üzerindeki etkisini araştırmak için de kullanıldı. Çalışmalar sonucunda çatlak uzunluğu/genişlik oranı (a/w) 0,1 olduğunda depolama basıncının 38 MPa olduğu, a/w oranı 0,5 olduğunda depolama basıncının 7 MPa değerine düştüğü belirlendi. Bu sonuçlardan tank gövdesindeki mevcut çatlakların çatlak uzunluğuna bağlı olarak depolama basıncını ciddi şekilde etkilediği sonucuna varılmıştır.
  • [ X ]
    Öğe
    Numerical Investigation of Effects of Different Injection Pressure on Diesel Engine Performance and NOX Emission
    (2021) Avcu, Adem; Tüccar, Gökhan; Choupanı, Naghdali
    Favourable efficiency of diesel engines makes them the most abundant type of internal combustion engines. However, diesel engines are also primary sources of particulate matter (PM) and nitrogen oxides (NOX) emissions formed as a result of the combustion process. There are many variables to affect the performance of diesel engine. One of them is injection pressure. Combustion process has a crucial effect on emission formation of diesel engines and this process is highly affected by fuel atomization. Injectors are one of the most important components of diesel engines that control the atomization of fuel. Today’s modern injectors provide high injection pressures to improve fuel atomization. To reduce exhaust emissions and fuel consumption, the effect of high-pressure fuel injection was investigated in fourcylinder engines numerically. Increased injection pressure improves smoke and fuel consumption, especially at low and medium speeds. However, some variables can be adversely affected by pressure increases. In this study, variables affecting engine performance were observed at different injection pressures for 500-800 bar and 800-1000 bar, and the results were shared.
  • [ X ]
    Öğe
    Red Mud Ratio Effects on the Tribological Performance of Fly-Ash-Reinforced Bronze Matrix Brake Pad Material
    (Springer, 2024) Kus, Husamettin; Avcu, Adem; Sugozu, Ilker
    Different amounts of red mud (0%, 2%, 4%, 6%, and 8%) were added to bronze matrix brake pad material reinforced with 12% fly ash and then hot-pressed at 800 degrees C and 40 MPa for 5 min. Wear-friction tests were conducted to determine the friction coefficient and specific wear rate, which are important indicators for evaluating the performance of brake pad samples. For all samples, the hardness and density were determined, fractured surfaces and microstructures were examined, and transverse rupture strength (TRS) was calculated using a three-point bending test. The hardness values of the samples increased with increasing red mud content, and their density values slightly decreased. TRS values of the samples increased with up to 4% red mud addition, but decreased when above 4%, and the friction coefficient of the brake pad samples decreased with an increase in red mud content. Moreover, all samples containing red mud, except the sample containing 2% red mud, showed a lower specific wear rate than the bronze matrix brake pad material reinforced with 12% fly ash. The worn surfaces of the specimens were also examined using scanning electron microscopy (SEM) and a 3D optical profilometer.