Afyon Kocatepe University Journal of Sciences and Engineering
Bu çalışmada, cam küre takviye fazlı polimer matrisli kompozit malzemenin delinmesi sonucu ortaya... more Bu çalışmada, cam küre takviye fazlı polimer matrisli kompozit malzemenin delinmesi sonucu ortaya çıkan delaminasyon faktörünün etkileri deneysel olarak incelenmiştir. Takviye fazı olarak ağırlıkça %5, %10 ve %20 takviye oranında cam küre kullanılmıştır. Matris malzemesi olarak Polipropilen tercih edilmiştir. Elde edilen sonuçlara göre, kesme hızı ve ilerleme arttıkça delaminasyon miktarında yükselmeler meydana gelmiştir. Elde edilen en düşük delaminasyon miktarı (1.18) 0.05 mm/devir ilerleme ve 15m/dk kesme hızında karbür takım türü ile elde edilmiştir. Ayrıca, kompozit içerisindeki takviye miktarı arttıkça delaminasyon faktörünün de yükseldiği saptanmıştır. En düşük delaminasyon miktarı %5 cam küre takviye içeren kompozit malzemede olmuştur.
Academic Platform Journal of Engineering and Science
Advanced high strength steels (AHSS) are newly developed steels that has versatile mechanical pro... more Advanced high strength steels (AHSS) are newly developed steels that has versatile mechanical properties. These steels enables to design low weight cars with high safety standards. Also, weight reduction in vehicles plays a significant role for saving fossil fuels which is limited and causes carbon emissions. Dual phase (DP) and Martensitic steels are prominent in AHSS family because they are inexpensive and has vast application areas. DP steels are used for general purpose applications and Martensitic steels are used for reinforcement parts in vehicles. In this study, high formable grade Dual phase steel with 800 MPa tensile strength and Martensitic steel with 1200 MPa tensile strength were welded with resistance spot welding technique which is the most widely practiced joining method in the industry. Electrode indentation depths, its effect on tensile-shear loads and microstructural characterizations were investigated. According to the results, the lowest tensile shear loads were acquired between both between 0-0.2 mm and between 0.85-1mm electrode plunge depths. Medial electrode plunge depths showed high tensile shear loads. Some welding defects were encountered including secondary phase formations, shrinkage voids, intergranular shrinkage gaps and vertical cracks in the weld nugget. It is find out that the weld defects were formed due to cooling gradient while solidifying, electrode force, and improper weld parameters.
Bu çalışmada, AHSS çelik ailesinden iki önemli çelik olan TWIP ve Martenzitik çeliklerinin birleş... more Bu çalışmada, AHSS çelik ailesinden iki önemli çelik olan TWIP ve Martenzitik çeliklerinin birleştirilmesi esnasında oluşan porozite problemi araştırılmıştır. Kaynak akımı ve kaynak süresinin porozite oluşumuna etkisi incelenmiştir. Porozitenin makro ve mikroskopik incelenmesi yapılmış ve porozitenin alan olarak oluşum miktarı kaynak parametreleri açısından incelenerek grafiksel olarak elde edilmiştir. Elde edilen bulgulara göre, kaynak süresi ve kaynak akımı arttıkça porozite miktarı artmıştır. En yüksek porozite miktarı 16.2% olarak 30 periyot kaynak süresi ve 12 kA kaynak akımında gerçekleşmiştir.
Alzheimer's disease is multi-component neurodegenerative disorder. Oxidative stress disrupts ... more Alzheimer's disease is multi-component neurodegenerative disorder. Oxidative stress disrupts regular functioning of metabolism in early-onset Alzheimer's disease. It causes Tau phosphorylation, formation of neurofibrillary tangle and neuron reduction. Due to intense binding of phosphorylated amino acids to aluminum, it induces self-assembly and deposition of high degree of phosphorylated cytoskeletal proteins, such as microtubule and neurofilament-associated proteins. In this study, it is aimed to consider the antioxidant potential of Hypericum perforatum extract against neurotoxicity caused by Aluminum-maltolate (Al(mal)3) and its effects on APP gene expression. Four different groups were determined to observe the impact of H. perforatum extract. After the incubation of the cells for 24 hours, only the medium was placed in the first group as control. 500 μM Al(mal)3 was added to the second group of cells. 20 μg mL-1 Hypericum perforatum extract was added to the third group....
Steel pipe piles are used to reinforce the grounds. Due to high hardness of the rocky materials, ... more Steel pipe piles are used to reinforce the grounds. Due to high hardness of the rocky materials, in some cases, the tip surface should be developed with new designs in terms of geometry, material and heat treatment. In this study, a hardfacing welding, which reinforces the application point of the tip surface, was applied on the steel pipe pile shoe tip which was manufactured from S355J2 steel. Wear tests were applied and hardness measurements were made to explain wear behavior. According to the results, the hardened surface of the 3rd layer which was welded with FCH-360 flux cored wire showed higher hardness than other layers. Similarly, the highest wear resistance was obtained in this layer. Martensitic and bainitic structures with ferrite islets were observed from the first layer to the second layer. The bainite and ferrite isles were gradually transformed to martensite and maintained itself from first to third layer. The martensitic structure mainly controlled the hardness and w...
Recently, to reduce car weight for saving fuel, reducing gas emissions, and to raise car safety b... more Recently, to reduce car weight for saving fuel, reducing gas emissions, and to raise car safety by selecting the optimum material that meets desired mechanical properties, Advanced High Strength Steels (AHSS) have been continuously in development. TWinning Induced Plasticity (TWIP) steels, that have high tensile strength with high elongation, and Martensitic steels, which tensile strengths can be raised up to 1700 Mpa, are among the most significant members of AHSS. However, strength of joints as important as the material itself. In an automotive body, the most practiced joining method is resistance spot welding. Tensile-peel test in resistance spot welding is of high importance, because its behavior akin to the breaking action of the sheet metal at the time of the accidents. In this study, tensile-peel strengths are investigated in terms of current and weld time using resistance spot welding. The weld time range is selected between 5-30 periods (a period 0,02 sec) with 5 period increments.
Kahramanmaraş Sütçü İmam Üniversitesi Mühendislik Bilimleri Dergisi, 2020
Bu çalışmada, tel çekme işleminde kalibrasyon uzunluğunun çekme mukavemeti üzerine olan etkisi in... more Bu çalışmada, tel çekme işleminde kalibrasyon uzunluğunun çekme mukavemeti üzerine olan etkisi incelenmiştir. Kalibrasyon bölgesinin etkisini iki farklı redüksiyon oranı ve filmaşin çapı kullanılarak gösterilmiştir. Elde edilen sonuçlara göre, kalibrasyon bölge uzunluğu arttıkça mukavemet artışı gözlemlenmiştir. Ancak, kalibrasyon boyunun uzun olması üretim esnasında çeşitli imalat problemlerine sebebiyet vermiştir. Çapsal mikrosertlik dağılımları ise kalibrasyon boyu arttıkça aralarındaki farklarda da artış gözlemlenmiştir. Mikrosertliğin artmasının esas sebebinin kalibrasyon boyunun artmasıyla elde edilen yüksek sürtünme kuvvetinin oluşturduğu deformasyon sertleşmesidir.
In recent years, some topics in Automotive industry has become important such as energy saving, c... more In recent years, some topics in Automotive industry has become important such as energy saving, carbon emission and automotive safety issues. The main motivation to meet these requirements is employing high strength and low weight materials for vehicles. Therefore, the conventional materials have been substituted with Advanced High Strength Steels (AHSS) and High Strength Low Alloy (HSLA) steels that have high strength-to-weight ratios. However, in addition to material investigation, the joining and welding of these materials is of high importance cannot be underestimated. In this work, weldability of TRIP 800 (transformation induced plasticity), a AHSS steel, and microalloyed steels, a HSLA steel, with resistance spot welding has been investigated. The effect of welding time parameter on tensile-shear properties was analyzed. The optimum parameters for tensile-shear strengths and the encountered separation modes have been examined. The highest tensile-shear loads was obtained using 15 periods.
Springs are widely used in machinery, tools and equipment for many purposes such as energy storag... more Springs are widely used in machinery, tools and equipment for many purposes such as energy storage and vibration damping. Prolonged vibration or oscillation and cycles induces crack propagation from the weak points on the spring. These crack initiations begin with the notch effect created by the external surface or the irregularities within the microstructure. As a result of the spring fatigue or unexpectedly ending its life, the machine can undergo irreversible damage to its dynamic structure [1]. Various techniques are used to calculate fatigue life of the springs during design. Some of them have been tried to calculate the spring life using the FEM (finite element method) method [2]. Other methods are various mathematical and numerical models that have been put forward [3, 4]. Although numerical models are used, there are various differences among these thecniques [5]. The main reason for the differences is due to outer and intrinsic factors such as microstructure characterization, surface hardness, surface roughness, application temperature and application frequencies [6, 7]. For this reason, simulating the fatigue of the springs in a real environment will give the most realistic result. Thus, irreversible damages can be prevented by determining the service life of the springs with the most accurate way [8]. Helical compression springs are among the most used spring types in the industry. This type of springs can be used in high-stress ranges where operating conditions are critical such as engines, pumps and valves [9]. The fatigue life of helical compression springs depends on many factors including the condition of the outer surface, surface roughness, internal structure of the material, discontinuities in the material, working load, capacity, and frequency [10]. Therefore, compression springs should be tested under real conditions. There are many spring fatigue machine designs in the industry. However, no study has been encountered that determines the life of compression springs produced from high strength wires driven with a pneumatic system. Fatigue testing applied to multiple compression springs was not also coincided in the literature. In this study, a fatigue machine simulating the working conditions of compression springs was designed and produced. The operation and design of the mechanical, electrical, pneumatic systems of the machine were carried out. The working efficiency of the fatigue
In this study, a compression spring fatigue problem arising from the galvanization process was in... more In this study, a compression spring fatigue problem arising from the galvanization process was investigated. Fatigue, crack initiation and growth of galvanized and non-galvanized springs manufactured from fully pearlitic high strength steel wires were investigated. According to the results, the galvanized compression springs exhibited a low fatigue life due to hydrogen embrittlement. Hydrogen embrittlement induced crack initiations formed under the galvanizing layer and adversely affect fatigue life. It was observed that local embrittlement on the outer surface of the spring wire causes crack initiations and disperses through the pearlitic interlamellar microstructure. Compared to non-galvanized and shot-peened specimens with the same surface roughness, compression springs, galvanized compression springs exhibited a 25 % reaction force loss at 50 000 cycles.
Introduction: Diabetic polyneuropathy (DPN) is a major chronic neurological complication of diabe... more Introduction: Diabetic polyneuropathy (DPN) is a major chronic neurological complication of diabetes mellitus (DM) and typically presents as diabetic sensory polyneuropathy (DSPN). Whereas some patients with similar risk factors develop polyneuropathy, others don't, which suggests that genetics plays an important role in the progression of disease. The proteasome modulator 9 gene (PSMD9) is a transcriptional regulator of the insulin gene and its variants cause beta-cell dysfunction that devastates insulin transcription. The aim of this study was to determine the correlation between PSMD9 rs14259 polymorphism and the risk of DSPN in Turkish DM patients with DPN. Methods: The study included 31 DM patients with DSPN and 29 healthy controls. All participants underwent electrophysiological investigation. In addition, DNA was isolated from peripheral blood samples for the genotyping of PSMD9 rs14259 polymorphism. Results: Mean age in the DSPN and control groups was 58.03±9.59 years and 57.62±12.32 years, respectively. There were significant differences between the DSPN and controls groups in the frequencies of the genotype for AA (n=9 and n=12, respectively), AG (n=10 and n=15, respectively), and GG (n=12 and n=2, respectively). According to the distribution of PSMD9 rs14259 polymorphism, 45.2% (n=28) of the patients and 67.2% (n=39) of the controls had the A allele, and 54.8% (n=34) of the patients and 32.8% (n=19) of the controls had the G allele, whereas the frequency of the G allele of rs14259 was significantly higher in the DSPN group (X 2 =1.059, P=0.015) than in the control group (OR: 2.49; 95% CI: 1.18-5.23). Conclusion: The present findings show that the GG genotype and G allele of PSMD9 rs14259 polymorphism may be associated with an increased risk of DSPN in Turkish DM patients.
Afyon Kocatepe University Journal of Sciences and Engineering
Bu çalışmada, cam küre takviye fazlı polimer matrisli kompozit malzemenin delinmesi sonucu ortaya... more Bu çalışmada, cam küre takviye fazlı polimer matrisli kompozit malzemenin delinmesi sonucu ortaya çıkan delaminasyon faktörünün etkileri deneysel olarak incelenmiştir. Takviye fazı olarak ağırlıkça %5, %10 ve %20 takviye oranında cam küre kullanılmıştır. Matris malzemesi olarak Polipropilen tercih edilmiştir. Elde edilen sonuçlara göre, kesme hızı ve ilerleme arttıkça delaminasyon miktarında yükselmeler meydana gelmiştir. Elde edilen en düşük delaminasyon miktarı (1.18) 0.05 mm/devir ilerleme ve 15m/dk kesme hızında karbür takım türü ile elde edilmiştir. Ayrıca, kompozit içerisindeki takviye miktarı arttıkça delaminasyon faktörünün de yükseldiği saptanmıştır. En düşük delaminasyon miktarı %5 cam küre takviye içeren kompozit malzemede olmuştur.
Academic Platform Journal of Engineering and Science
Advanced high strength steels (AHSS) are newly developed steels that has versatile mechanical pro... more Advanced high strength steels (AHSS) are newly developed steels that has versatile mechanical properties. These steels enables to design low weight cars with high safety standards. Also, weight reduction in vehicles plays a significant role for saving fossil fuels which is limited and causes carbon emissions. Dual phase (DP) and Martensitic steels are prominent in AHSS family because they are inexpensive and has vast application areas. DP steels are used for general purpose applications and Martensitic steels are used for reinforcement parts in vehicles. In this study, high formable grade Dual phase steel with 800 MPa tensile strength and Martensitic steel with 1200 MPa tensile strength were welded with resistance spot welding technique which is the most widely practiced joining method in the industry. Electrode indentation depths, its effect on tensile-shear loads and microstructural characterizations were investigated. According to the results, the lowest tensile shear loads were acquired between both between 0-0.2 mm and between 0.85-1mm electrode plunge depths. Medial electrode plunge depths showed high tensile shear loads. Some welding defects were encountered including secondary phase formations, shrinkage voids, intergranular shrinkage gaps and vertical cracks in the weld nugget. It is find out that the weld defects were formed due to cooling gradient while solidifying, electrode force, and improper weld parameters.
Bu çalışmada, AHSS çelik ailesinden iki önemli çelik olan TWIP ve Martenzitik çeliklerinin birleş... more Bu çalışmada, AHSS çelik ailesinden iki önemli çelik olan TWIP ve Martenzitik çeliklerinin birleştirilmesi esnasında oluşan porozite problemi araştırılmıştır. Kaynak akımı ve kaynak süresinin porozite oluşumuna etkisi incelenmiştir. Porozitenin makro ve mikroskopik incelenmesi yapılmış ve porozitenin alan olarak oluşum miktarı kaynak parametreleri açısından incelenerek grafiksel olarak elde edilmiştir. Elde edilen bulgulara göre, kaynak süresi ve kaynak akımı arttıkça porozite miktarı artmıştır. En yüksek porozite miktarı 16.2% olarak 30 periyot kaynak süresi ve 12 kA kaynak akımında gerçekleşmiştir.
Alzheimer's disease is multi-component neurodegenerative disorder. Oxidative stress disrupts ... more Alzheimer's disease is multi-component neurodegenerative disorder. Oxidative stress disrupts regular functioning of metabolism in early-onset Alzheimer's disease. It causes Tau phosphorylation, formation of neurofibrillary tangle and neuron reduction. Due to intense binding of phosphorylated amino acids to aluminum, it induces self-assembly and deposition of high degree of phosphorylated cytoskeletal proteins, such as microtubule and neurofilament-associated proteins. In this study, it is aimed to consider the antioxidant potential of Hypericum perforatum extract against neurotoxicity caused by Aluminum-maltolate (Al(mal)3) and its effects on APP gene expression. Four different groups were determined to observe the impact of H. perforatum extract. After the incubation of the cells for 24 hours, only the medium was placed in the first group as control. 500 μM Al(mal)3 was added to the second group of cells. 20 μg mL-1 Hypericum perforatum extract was added to the third group....
Steel pipe piles are used to reinforce the grounds. Due to high hardness of the rocky materials, ... more Steel pipe piles are used to reinforce the grounds. Due to high hardness of the rocky materials, in some cases, the tip surface should be developed with new designs in terms of geometry, material and heat treatment. In this study, a hardfacing welding, which reinforces the application point of the tip surface, was applied on the steel pipe pile shoe tip which was manufactured from S355J2 steel. Wear tests were applied and hardness measurements were made to explain wear behavior. According to the results, the hardened surface of the 3rd layer which was welded with FCH-360 flux cored wire showed higher hardness than other layers. Similarly, the highest wear resistance was obtained in this layer. Martensitic and bainitic structures with ferrite islets were observed from the first layer to the second layer. The bainite and ferrite isles were gradually transformed to martensite and maintained itself from first to third layer. The martensitic structure mainly controlled the hardness and w...
Recently, to reduce car weight for saving fuel, reducing gas emissions, and to raise car safety b... more Recently, to reduce car weight for saving fuel, reducing gas emissions, and to raise car safety by selecting the optimum material that meets desired mechanical properties, Advanced High Strength Steels (AHSS) have been continuously in development. TWinning Induced Plasticity (TWIP) steels, that have high tensile strength with high elongation, and Martensitic steels, which tensile strengths can be raised up to 1700 Mpa, are among the most significant members of AHSS. However, strength of joints as important as the material itself. In an automotive body, the most practiced joining method is resistance spot welding. Tensile-peel test in resistance spot welding is of high importance, because its behavior akin to the breaking action of the sheet metal at the time of the accidents. In this study, tensile-peel strengths are investigated in terms of current and weld time using resistance spot welding. The weld time range is selected between 5-30 periods (a period 0,02 sec) with 5 period increments.
Kahramanmaraş Sütçü İmam Üniversitesi Mühendislik Bilimleri Dergisi, 2020
Bu çalışmada, tel çekme işleminde kalibrasyon uzunluğunun çekme mukavemeti üzerine olan etkisi in... more Bu çalışmada, tel çekme işleminde kalibrasyon uzunluğunun çekme mukavemeti üzerine olan etkisi incelenmiştir. Kalibrasyon bölgesinin etkisini iki farklı redüksiyon oranı ve filmaşin çapı kullanılarak gösterilmiştir. Elde edilen sonuçlara göre, kalibrasyon bölge uzunluğu arttıkça mukavemet artışı gözlemlenmiştir. Ancak, kalibrasyon boyunun uzun olması üretim esnasında çeşitli imalat problemlerine sebebiyet vermiştir. Çapsal mikrosertlik dağılımları ise kalibrasyon boyu arttıkça aralarındaki farklarda da artış gözlemlenmiştir. Mikrosertliğin artmasının esas sebebinin kalibrasyon boyunun artmasıyla elde edilen yüksek sürtünme kuvvetinin oluşturduğu deformasyon sertleşmesidir.
In recent years, some topics in Automotive industry has become important such as energy saving, c... more In recent years, some topics in Automotive industry has become important such as energy saving, carbon emission and automotive safety issues. The main motivation to meet these requirements is employing high strength and low weight materials for vehicles. Therefore, the conventional materials have been substituted with Advanced High Strength Steels (AHSS) and High Strength Low Alloy (HSLA) steels that have high strength-to-weight ratios. However, in addition to material investigation, the joining and welding of these materials is of high importance cannot be underestimated. In this work, weldability of TRIP 800 (transformation induced plasticity), a AHSS steel, and microalloyed steels, a HSLA steel, with resistance spot welding has been investigated. The effect of welding time parameter on tensile-shear properties was analyzed. The optimum parameters for tensile-shear strengths and the encountered separation modes have been examined. The highest tensile-shear loads was obtained using 15 periods.
Springs are widely used in machinery, tools and equipment for many purposes such as energy storag... more Springs are widely used in machinery, tools and equipment for many purposes such as energy storage and vibration damping. Prolonged vibration or oscillation and cycles induces crack propagation from the weak points on the spring. These crack initiations begin with the notch effect created by the external surface or the irregularities within the microstructure. As a result of the spring fatigue or unexpectedly ending its life, the machine can undergo irreversible damage to its dynamic structure [1]. Various techniques are used to calculate fatigue life of the springs during design. Some of them have been tried to calculate the spring life using the FEM (finite element method) method [2]. Other methods are various mathematical and numerical models that have been put forward [3, 4]. Although numerical models are used, there are various differences among these thecniques [5]. The main reason for the differences is due to outer and intrinsic factors such as microstructure characterization, surface hardness, surface roughness, application temperature and application frequencies [6, 7]. For this reason, simulating the fatigue of the springs in a real environment will give the most realistic result. Thus, irreversible damages can be prevented by determining the service life of the springs with the most accurate way [8]. Helical compression springs are among the most used spring types in the industry. This type of springs can be used in high-stress ranges where operating conditions are critical such as engines, pumps and valves [9]. The fatigue life of helical compression springs depends on many factors including the condition of the outer surface, surface roughness, internal structure of the material, discontinuities in the material, working load, capacity, and frequency [10]. Therefore, compression springs should be tested under real conditions. There are many spring fatigue machine designs in the industry. However, no study has been encountered that determines the life of compression springs produced from high strength wires driven with a pneumatic system. Fatigue testing applied to multiple compression springs was not also coincided in the literature. In this study, a fatigue machine simulating the working conditions of compression springs was designed and produced. The operation and design of the mechanical, electrical, pneumatic systems of the machine were carried out. The working efficiency of the fatigue
In this study, a compression spring fatigue problem arising from the galvanization process was in... more In this study, a compression spring fatigue problem arising from the galvanization process was investigated. Fatigue, crack initiation and growth of galvanized and non-galvanized springs manufactured from fully pearlitic high strength steel wires were investigated. According to the results, the galvanized compression springs exhibited a low fatigue life due to hydrogen embrittlement. Hydrogen embrittlement induced crack initiations formed under the galvanizing layer and adversely affect fatigue life. It was observed that local embrittlement on the outer surface of the spring wire causes crack initiations and disperses through the pearlitic interlamellar microstructure. Compared to non-galvanized and shot-peened specimens with the same surface roughness, compression springs, galvanized compression springs exhibited a 25 % reaction force loss at 50 000 cycles.
Introduction: Diabetic polyneuropathy (DPN) is a major chronic neurological complication of diabe... more Introduction: Diabetic polyneuropathy (DPN) is a major chronic neurological complication of diabetes mellitus (DM) and typically presents as diabetic sensory polyneuropathy (DSPN). Whereas some patients with similar risk factors develop polyneuropathy, others don't, which suggests that genetics plays an important role in the progression of disease. The proteasome modulator 9 gene (PSMD9) is a transcriptional regulator of the insulin gene and its variants cause beta-cell dysfunction that devastates insulin transcription. The aim of this study was to determine the correlation between PSMD9 rs14259 polymorphism and the risk of DSPN in Turkish DM patients with DPN. Methods: The study included 31 DM patients with DSPN and 29 healthy controls. All participants underwent electrophysiological investigation. In addition, DNA was isolated from peripheral blood samples for the genotyping of PSMD9 rs14259 polymorphism. Results: Mean age in the DSPN and control groups was 58.03±9.59 years and 57.62±12.32 years, respectively. There were significant differences between the DSPN and controls groups in the frequencies of the genotype for AA (n=9 and n=12, respectively), AG (n=10 and n=15, respectively), and GG (n=12 and n=2, respectively). According to the distribution of PSMD9 rs14259 polymorphism, 45.2% (n=28) of the patients and 67.2% (n=39) of the controls had the A allele, and 54.8% (n=34) of the patients and 32.8% (n=19) of the controls had the G allele, whereas the frequency of the G allele of rs14259 was significantly higher in the DSPN group (X 2 =1.059, P=0.015) than in the control group (OR: 2.49; 95% CI: 1.18-5.23). Conclusion: The present findings show that the GG genotype and G allele of PSMD9 rs14259 polymorphism may be associated with an increased risk of DSPN in Turkish DM patients.
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