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Öğe AA7075 Yaşlandırılmasında Farklı Ön Gerinmelerin Mekanik Özelliklere Etkilerinin İncelenmesi(2019) Kılıç, Süleyman; Kacar, İlyas; Öztürk, Fahrettin; Şahin, Mevlüt; Erdem, OğuzBu çalışmada havacılık sanayinde yaygın kullanıma sahip 7075 alüminyum alaşımının yaşlandırılmasında farklı ön gerinmelerin alaşımınmekanik özelliklerine etkileri incelenmiştir. Çalışmadaki temel amaç farklı oranlarda ön şekillendirilmiş yapısal parçaların boya fırınlamasıesnasındaki mekanik ve mikroyapı özelliklerinin değişiminin belirlenmesidir. Boya fırınlama işlemlerinde genellikle 120-200 ºC sıcaklıklarıkullanılmaktadır. Bu kapsamda çalışmamızda yaşlandırma sıcaklıkları 120, 160 ve 200 ºC olarak seçilmiştir. Numunelere farklı ön gerinmeleruygulanarak ön gerinmenin yaşlandırmadaki etkisi detaylı olarak incelenmiştir. İncelemeler sonucunda ön gerinmenin artmasıyla,200 ºC yaşlandırma sıcaklığında akma mukavemeti ve geri esneme düşerken, altındaki yaşlandırma sıcaklıklarında artmaktadır. Bunun sebebiise mikroyapıdaki MgZn2 katı çökeltilerinin hacimsel miktarıdırÖğe Characterization of heating elements of different dimensions used in resistance welding of thermoplastic matrix composite materials(2023) Öztürkmen, Hakan; Usta, Yusuf; Toros, Serkan; Öztürk, FahrettinResistance welding is one of the most useful methods for joining of thermoplastic composite materials. In this method, the joining process between two thermoplastic composite materials by passing a current through a stainless-steel heating element under pressure for a certain period. Within the scope of this study, meshes with a width of 12.7, 25.4, 38.1, 50.8, 63.5, 76.2 mm and a length of 160 mm were used to characterize the joule heating performance. These meshes have a mesh range of 33, 45, 61, 91, 109 and 154 microns. The temperature values on the heating elements were observed with a thermal camera by giving different current values to the relevant elements. Results reveal that the 12.7 x 160 mm heating element with 33-micron mesh spacing reached 349 °C under 10 A current, and the temperature value increased with current. In addition, it was determined that the resistance values of the heating elements with different widths were determined by the relevant system and the resistance properties changed non-linearly with the width.Öğe Effects of different optimization methods on the predictions of YLD2000 yield criterion coefficients(Niğde Ömer Halisdemir Üniversitesi, 2019) Kılıç, Süleyman; Kacar, İlyas; Öztürk, Fahrettin; Toros, SerkanThe improved yield criteria are generally used in the finite element simulations of plastic deformation processes. Calculation accuracies of these criteria coefficients result successful simulation outcomes. In this study, the coefficients of the YLD2000 yield criterion are calculated by three most widely used optimization methods in literature, namely the least squares, nonlinear conditional optimization, and genetic algorithm methods. Two different aluminum alloys, AA7003-T6 and AA6063-T6 are selected to verify the prediction results. Results reveal that the nonlinear conditional optimization and genetic algorithm methods are very dependent on the initial values. Therefore, different result is determined for each different case. For this reason, it has been concluded that the least squares method should be preferred to calculate the coefficients of the yield criterion by using optimizing method.Öğe EFFECTS OF DIFFERENT OPTIMIZATION METHODS ON THE PREDICTIONS OF YLD2000 YIELD CRITERION COEFFICIENTS(2019) Kılıç, Süleyman; Kacar, İlyas; Öztürk, Fahrettin; Toros, SerkanThe improved yield criteria are generally used in the finite element simulations of plastic deformationprocesses. Calculation accuracies of these criteria coefficients result successful simulation outcomes. In thisstudy, the coefficients of the YLD2000 yield criterion are calculated by three most widely used optimizationmethods in literature, namely the least squares, nonlinear conditional optimization, and genetic algorithmmethods. Two different aluminum alloys, AA7003-T6 and AA6063-T6 are selected to verify the predictionresults. Results reveal that the nonlinear conditional optimization and genetic algorithm methods are verydependent on the initial values. Therefore, different result is determined for each different case. For this reason,it has been concluded that the least squares method should be preferred to calculate the coefficients of the yieldcriterion by using optimizing method.Öğe İki eksenli gerdirme testi datalarının ince saç metal şekillendirme sonlu elemanlar yazılımlarında kullanımının araştırılması(2010) Öztürk, Fahrettin[Abstract Not Available]Öğe İki fazlı çeliklerde şekillendirme hızının etkisinin incelenmesi(2010) Öztürk, Fahrettin[Abstract Not Available]Öğe INVESTIGATION OF EFFECT ON THE MECHANICAL PROPERTIES OF QUENCHING TEMPERATURE IN AA7075(2020) Kılıç, Süleyman Sırrı; Kacar, İlyas; Şahin, Mevlut; Öztürk, Fahrettin; Oğuz, ErdemIn this study, effect of quenching temperature on mechanical properties of Aluminum Alloy 7075 (AA7075) are investigated. Several quenching environment is tested oil (20W50), icy water (2 oC), water (25 oC), and hot water (85 oC). Mechanical properties of the materials are measured. X-ray diffraction analyses are also performed for each condition. Results indicated thatproperties at hot water quenching and oil quenching are found to be similar. It is concluded that oil quenching does not have significant effect on mechanical properties.Öğe New trend in aerospace industry: Al-Li based alloys(Gazi Universitesi Muhendislik-Mimarlik, 2019) Kılıç, Süleyman; Kacar, İlyas; Öztürk, FahrettinAl-Li (Aluminum-Lithium) alloys have become the focus of the aerospace industry due to their low density and high elasticity modulus, excellent corrosion resistance, high hardness, high fatigue crack growth resistance, and low fracture toughness. Alloys continue to be used in various structural parts of the aircrafts such as seat beams, floor beams and columns, wing beams, cradle frames, and research studies are intensively going on about its future use for other structural parts. As with all materials, there are various problems in these alloys. In this study, the use of Al-Li based alloys in the aerospace industry, the problems encountered, and the proposal of solutions have been examined. © 2019 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved.Öğe Sıcaklık ve deformasyon hızının şekillendirilebilmeye etkisinin deneysel ve teorik olarak incelenmesi(2008) Öztürk, Fahrettin; Alkan, Mahmut[Abstract Not Available]
