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Warm Hydromechanical Deep Drawing (WHDD) is considered as an effective sheet metal forming process to overcome low formability problems of lightweight materials, such as aluminum and magnesium alloys, at room temperature. WHDD process combines the advantages of Hydromechanical Deep Drawing (HDD) and Warm Deep Drawing (WDD) processes. In this study, interactive and combined effects of Pressure (P) and Blank Holder Force (BHF) variation on the formability of the AA 5754 aluminum alloy sheets in the WHDD process were investigated experimentally and numerically. Different from available studies, the optimal fluid pressure (P) and blank holder force (BHF) profiles, which were determined numerically using adaptive FEA integrated with fuzzy logic control algorithm (aFEA-FLCA), were validated experimentally for the first time in literature. Consequently, limiting drawing ratios (LDR) of AA5754 material were recorded as 2.5, 2.625, and 3.125 for HDD, WDD, and WHDD processes, respectively. Thus, it was demonstrated that the formability of lightweight materials, such as AA5754, could be increased significantly using the WHDD process through the proposed optimization method. This method was also implemented into the WHDD of an industrial part with complex geometry, successfully forming sharp features with minimal thinning at reduced levels of force, pressure, and time. Consequently, it is reasonably to state that the method developed in this study can be adopted for the manufacturing of any other part using the WHDD process.

Bu çalışmada sac metal ürün üretiminde, hızlı ve ekonomik bir üretim talebini karşılamak için, klasik derin çekmeyle birçok kademede üretilen çaydanlığın daha az kademede üretilmesi amacıyla hidroşekillendirme kalıplarının tasarım ve imalatı gerçekleştirilmiştir. Kalıp ve yöntem parametrelerinin belirlenmesinde bulanık mantık algoritmalarına dayalı adaptif kontrol uygulamalı Sonlu Elemanlar Analizleri kullanılmıştır. Endüstriyel ürünün üretilmesi için gerekli büyük boyutlu, dolayısıyla çok maliyetli, 1:1 ölçekli kalıplar üretilmeden önce, çok daha düşük maliyetli 1:4 ölçekli kalıplar üretilerek laboratuvar presinde belirlenen kalıp ve yöntem parametrelerinin benzetim yöntemi ile 1:1 ölçekli kalıplarda da geçerliliği araştırılmıştır. Bu amaca ulaşmak için 100 MPa sıvı basıncı ve 10000 kN kapasiteli sanayi tipi bir sac hidroşekillendirme presi kullanılmıştır.Laboratuvar çalışmaları sonunda, 1:4 ölçekli kalıplardan elde edilen kalıp ve yöntem parametreleri kullanılarak 1:1 ölçekli kalıplarla hidromekanik sıvama yöntemi uygulanmıştır. Klasik sıvama ile 4 kademede şekillendirilebilen çaydanlık hidromekanik sıvama yöntemi ile tek kademede başarıyla üretilebilmiştir. Böylece endüstriyel ürünün üretilmesi için gerekli olan 1:1 ölçekli kalıplar üretilmeden önce benzetim kurallarına uygun olarak 1:4 ölçekli model kalıplarla sızdırmazlık sistemi ve yöntem parametrelerinin belirlenmesiyle maliyete önemli bir katkı sağlanmıştır. Hidromekanik sıvama yöntemi ile klasik sıvama yöntemi, üretim hızı ve kalınlık dağılımı açısından kıyaslanmıştır. Klasik sıvama yöntemi ile 4 kademede üretilen çaydanlığın üretim süresi presler arası taşıma süresi de dikkate alındığında yaklaşık 60 saniyedir. Çaydanlık hidromekanik sıvama yöntemi ile tek kademede 50 saniyede üretilebilmiştir. Böylece klasik sıvamaya göre üretim hızı yaklaşık %20 artırılmıştır. Kalınlık dağılımları incelendiğinde ise hidromekanik sıvama yöntemi ile üretilen çaydanlığın kalınlık dağılımının klasik sıvamayla üretilene göre daha üniform olduğu görülmüştür. Geometrik toleranslar açısından değerlendirildiğinde ise hidromekanik sıvama yöntemi ile üretilen parçalardaki toleransların, klasik sıvama ile elde edilenlere göre yaklaşık aynı olduğu tespit edilmiştir.

Bu çalışmada dalma elektro erozyonla islemede (EDM), iş parçasında boşluğu oluşturacak model kullanmak yerine, kaba işlemede dikdörtgen ceplerin boşaltılmasında genel amaçlı küresel uçlu takım elektrotların kullanılabilirliği araştırılmıştır. CNC EDM tezgâhında en düşük aşınma ve birim zamanda en çok talaş kaldırmayı sağlayacak kaba işleme parametreleri kullanılarak elektrot geometrisini en az değiştirecek iki alternatif takım yolu denenmiştir. Takım elektrotlar EDM tezgâhında işleme yapmadan önce ve işleme yaptıktan sonra optoTOP-HE 3B optik ölçme sistemi ile ölçülmüştür. Rapidform 2004 PPS yazılımı kullanılarak 3B verilerden elektrotlara ait küre merkez koordinatları, elektrotlarda oluşan aşınmalar ve üretilen boşlukların ideal boşluklardan sapmaları bulunmuştur. Ayrıca, dikdörtgen ceplerin boşaltılması için kullanılabilecek bir CNC EDM CAM programı için, temel bir algoritma önerilmiştir. Takım elektrot yarıçapı ve takım kompanzasyonu değişimlerinin bulunabildiği bu algoritmanın doğruluğu, deneylerden elde edilen verilerin simülasyonu ile karşılaştırılarak kanıtlanmıştır. Daha sonraki çalışmalara ışık tutması için, rastgele eğrilerden oluşan cep boşaltmada, küre yarıçapının ve takım elektrot kompanzasyonunun doğru denklemleri ile temsil edilebileceği konusunda öneriler yapılmıştır.

Yapılan bu çalışmada kesme operasyonunun özellikle son yıllarda birçok alanda yaygın olarak kullanılmayabaşlanan hidro şekillendirme prosesine uyarlanabilirliğinin nümerik olarak değerlendirilmesi yapılmıştır.Nümerik çalışmalar kapsamında malzemenin kesilme yüzeyleri değerlendirilmiş ve çapak oluşum durumuzımbanın farklı hareketi için incelenmiştir. Modelleme çalışması kapsamında Johnson-Cook (J-C) pekleşme vehasar modeli kullanılarak, hedeflenen proses parametrelerinde kesme durumunun gerçekleşip gerçekleşmediğibelirlenmeye çalışılmıştır. Sonuç olarak hedef proses parametrelerinde 304 paslanmaz çeliğin bu proses ilekesilebilirliği gösterilmiştir., In this study, numerical evaluation of the adaptability of the cutting operation to the hydroforming process,which has been widely used in many areas especially in recent years, has been made. In the numerical studies,the cut surfaces of the material were evaluated and the burr formation state was investigated for the differentmovement of the punch. Within the scope of the modeling study, it was tried to determine whether the cuttingcondition in the target process parameters was realized by using the Johnson-Cook (J-C) hardening and damagemodel. As a result, 304 stainless steel can be cut by this process in target process parameters.

An experimental study was conducted on vapor compression refrigerators using R134a refrigerant for the purpose of achieving energy recovery and decreasing the effects of irreversibility. An ejector was used as an expander instead of an expansion valve. The coefficient of performance of the ejector refrigeration system and the amount of irreversibility and efficiency of each of its components were determined and compared with those of a basic vapor compression refrigeration system of the same cooling capacity under the same external conditions. It was found that the ejector expander system exhibited a lower total irreversibility in comparison with the basic system. When the ejector was used as the expander in the refrigeration system, the coefficient of performance was higher than in the basic system by 7.34-12.87%, while the exergy efficiency values were 6.6-11.24% higher than in the basic system. (C) 2014 Elsevier Ltd. All rights reserved.

Warm hydromechanical deep drawing (WHDD) has increasingly been implemented by automotive industry due to its various benefits including mass reduction opportunities in auto body-in-white components and improved formability for lightweight alloys. In the first part of the current study, WHDD of AA 5754-O was studied. In order to obtain the highest formability, an optimization study was performed for AA 5754-O WHDD process parameters (tool temperature, hydraulic pressure (HP), and blank holder force (BHF) loading profiles) through finite element analysis (FEA) + experimentation approach. Results showed that the optimal temperature for punch is 25 °C and 300 °C for die and blank holder. In addition, HP was found to be more effective on formability when compared to BHF. Both fast increasing HP and blank holder loading profiles contributes to higher formability.

Sac şekillendirme proseslerinde, sacın istenen şekli alması bölgesel boyunlaşma ve yırtılma hasarları tarafından sınırlanır. Bu proseslerde malzeme davranışını tahmin etmek için bilgisayar modelleri geliştirilmiştir. Bu modellerin gerçek durumu temsil edebilmesi için malzeme parametrelerine ihtiyaç vardır. Bu parametrelergenellikle çekme deneyi ve şekillendirme sınırını belirten diyagramlar ile elde edilir. Şekillendirme sınırınıbelirten diyagramlar sınır birim şekil değiştirme değerlerini gösteren şekillendirme sınır diyagramı ve sınırgerilme değerlerini gösteren şekillendirme sınır gerilme diyagramıdır. Şekillendirme sınır diyagramının hasar tahminini karmaşık ve birden fazla kademeli şekillendirme işlemlerinde doğru olarak tahmin edemediği, şekillendirme sınır gerilme diyagramının ise bu durumlarda da başarılı hasar tahminlerinde bulunduğu literatürde belirtilmektedir. Bu çalışmada Al 5754-O malzemeye ait şekillendirme sınır gerilme diyagramı hem teorik hem de sayısal yöntemle elde edilmiştir., In sheet metal forming processes, local necking and fracture failures limit sheet metal form to desired shape.Computer models have been developed to estimate the material behavior in these processes. Material parametersare needed to represent the real forming processes. These parameters are generally obtained from tensile test andforming limit diagram. Diagrams that specify formability limit are forming limit diagram shows limit strains andforming limit stress diagram shows limit stresses. In literature, it is remarked that while forming limit diagram cannot estimate the failures for complex andgradual forming processes, forming limit stress diagram can successfully.

Sac metal parçaların kalınlık dağılımlarının belirlenmesinde en pratik çözümlerden birisi üç boyutlu (3B) tarama yöntemidir. Sac parçaların belirli bir kesitinden kesilerek, profil projeksiyon, SEM gibi hassas cihazlarla sadece o kesitinden ölçüm yapılması yerine, bu yöntemde, parça kesilmeden, tüm parça boyunca kalınlık dağılımları belirlenebilmektedir. Özellikle anizotropik davranış gösteren sac metal malzemeler için bu durum daha da önemlidir. Ancak, 3B tarama yöntemi ile sac parçaların taranmasında, iç ve dış yüzeyler arasında geçiş yaparken, ortak referans noktaların yakalanacağı bir açının elde edilmesi zordur. Parçaların iç ve dış yüzeyleri ayrı ayrı tarandığı zaman da, yüzeylerin eşleştirilmesinde problem yaşanmaktadır. Bu çalışmada, bahsedilen problemin çözümü için numunelerin flanş bölgelerine, farklı açılardan rahatça görülebilecek dikdörtgenler prizması şeklindeki referans parçaları yapıştırılmıştır. Bu sayede iç ve dış yüzeyler arası geçiş sağlanmıştır. 3B tarama yönteminin sac metal parçaların kalınlık dağılımlarının belirlenmesinde güvenle kullanılabileceğini test etmek için, şekillendirilmiş sac metal parçaların kalınlık dağılımları, 3B tarama, profil projeksiyon ve SEM ile ölçülmüş olup sonuçlar birbirleriyle karşılaştırılmıştır. Sonuç olarak, farklı yöntemlerle elde edilen kalınlık dağılımlarının birbirleriyle oldukça uyumlu olduğu görülmüştür. Dolayısıyla 3B yöntemi ile sac parçaların kalınlık dağılımlarının hassas olarak belirlenebileceği tespit edilmiştir. Böylece tersine mühendislik yoluyla 3B verileri elde edilen ince cidarlı derin parçalar 3B yazıcılarla hassas olarak üretilebilecektir. Ayrıca, sac metal parçaların geometrilerinin ölçülmesiyle kalite kontrol yapılarak Endüstri 4.0'ın alt yapısına kolaylık sağlamış olacaktır., One of the most practical methods is 3D scanning method for thickness distribution of the sheet metal parts. In this method, thickness distribution through whole part can be determined without cutting, instead of only cutting section with using sensitive device such as profile projector and SEM. It is very important for especially sheet metals which show anisotropic behavior. However, during scanning sheet metal part, catching the partner reference points during translate from inner surface to outer surface is very hard work. When the inner and the outer surfaces of the sheet metal are separately scanned, match-up the surfaces is problem. In this research, a reference rectangular solid part which is easily seen at different angles on the flange region of the sheet part has been glued in order to overcome this problem. So, transition between the inner and outer surfaces has been provided. The thickness distributions of the deformed parts are measured by 3D scanning method, profile projector and SEM to test the reliability of 3D scanning method for determination of the thickness distribution of the sheet metal parts. The obtained results have been compared with each other. Consequently, it is shown that the thickness distributions obtained from different methods are compatible with each other. Hence, it is concluded that 3D scanning method is reliably used for determination of the thickness distribution of the sheet metal. So, the thin-walled deep parts which are obtained the 3D data with using inverse engineering can be sensitively produced by 3D printing method. Moreover, the measurement of geometries of sheet metal parts using scanning device by performing quality control contributes the infrastructure of the Industry 4.0.

In this paper, a new method was proposed in order to enhance the limiting drawing ratio (LDR) of AA5754-O in the hydromechanical deep drawing process (HDD). In the proposed method, a shallow drawbead was added to the blank holder to increase LDR so as to provide strain hardening of a large region on the flange of the sheet material in addition to pre-bulging process which affects particularly only the initial stage but not the later ongoing process. So the LDR of the AA5754-O was increased from 2.65 to 2.787 by enlarging the region of strain hardening in the flange and partially reducing wrinkling tendency due to occurred tensile stresses using the convenient pressure and blank holder force profiles. The importance levels and their convenient values for height of drawbead, pre-bulge height and pressure, surface roughness of the punch were determined with analysis of variance (ANOVA) is a statistical method. ANOVA analysis illustrated that adding a shallow drawbead to the blank holder is the most effective factor between the investigated factors for the HOD process. While the effects of the pre-bulging pressure and pre-bulging height were determined as quite small, the surface roughness of the punch was found unimportant compared to the effect of the shallow drawbead. The highest LDR value was obtained with 1 mm drawbead height, 5 mm pre-bulging height, 10 MPa pre-bulging pressure and 2.8 mu m surface roughness of the punch. (C) 2014 Elsevier B.V. All rights reserved.

Aluminum alloys have good properties such as high strength-to-weight ratio, corrosion resistance and relatively low cost. Nowadays they are primarily used as wrought and cast in many industries such as automotive, aviation and aerospace because of these properties. Aluminum alloys are classified into two categories as non-heat-treatable and heat-treatable. The mechanical properties of the heat-treatable alloys are improved by solution heat treatment and controlled ageing. While mechanical properties of some heat-treatable alloys, especially 2XXX series, become stable with natural ageing at room temperature within a few days, some of them are unstable and exhibit significant changes in properties even after many years. Heat treatment process of AA 2024 is very sensible and critical and therefore should be carefully performed. In this research, effects of the solution temperature, soaking time, heating rate and quenching delay condition of AA 2024 on the mechanical properties were investigated.

Formability of sheet metals can be increased by Hydromechanical Deep Drawing (HDD) process. Formability of the deep drawn cups is generally assessed by Limiting Drawing Ratio (LDR) which is the ratio of the blank diameter to punch diameter. In order to increase LDR by HDD, process parameters of the HDD should be arranged properly. Arranging of the process parameters requires a great knowledge about the effects of the process parameters to certain performance criteria of the process. Determining of the effects of the process parameters by full factorial experiments is a hard duty. Hence certain statistical methods that decrease the number and the cost of the experiments and reduce the time should be used to find effective parameters and their appropriate levels. In this study orthogonal experimental array was applied and effective process parameters were determined by analyzing predicted data with Taguchi's robust parameter design method and ANOVA method. Then the results were compared with each other to evaluate differences between the methods. By using the appropriate levels of the parameters the LDR of AA 5754 aluminum alloy which uses in automotive industry intensely was determined.

Deep drawn parts usually have different wall heights because of earing behavior. This behavior is due to the planar anisotropy (Δr) of sheet metals. A measure of the variation of normal anisotropy with the angel to the rolling direction in sheet plane is known as planar anisotropy. If the magnitude of the planar anisotropy is relatively large as absolute value, the earing behavior becomes more effective so larger ears occur. Furthermore, the orientation of the sheet with respect to the die or the part to be formed will be important. In addition, cutting of scraps in the parts which have ears leads to material waste. The scope of this study is to determine the planar anisotropy of AA 5754-O and AA 2024-T4 aluminum alloys and to investigate the earing behavior by the way of deep drawing of cylindrical cups.

2nd International Conference on Mechanical, System and Control Engineering, ICMSC 2018 -- 21 June 2018 through 23 June 2018 -- 141803, The hydroforming method is especially used for forming lightweight materials like aluminum, magnesium alloys, high strength steels or materials that have limited formability. Intensifiers are the most important component of hydroforming presses. Nowadays single-Acting intensifiers are used in hydroforming presses. Single-Acting intensifiers provide pressurized liquid by forwarding movement of the piston through one direction and their volumes are limited. The mass of the intensifiers increases significantly depending on their liquid volume capacity and this causes high manufacturing costs. For this reason, two or more single-Acting intensifiers which bridged in a parallel circuit are used to manufacture bigger products that require a high volume of liquid. But this method is not an economical solution. So double-Acting intensifiers can overcome this problem. The pressurized liquid can be obtained during both forward and backward movement of the piston in double-Acting intensifiers which work like a pump. This is why double-Acting intensifiers have no volume limit on the contrary of single-Acting intensifiers. Yet there are sudden pressure drops in double-Acting intensifiers caused by returning movements of the piston to pressurize liquid again. This pressure drops cause some problems to use double-Acting intensifiers on hydroforming method. The situation of solving this problem to use double-Acting intensifiers on the hydroforming method can eliminate limited volume problem and decrease investment cost of hydroforming presses. In this study, the usability of double-Acting intensifiers on hydroforming with die method was investigated. Because of the existing hydroforming press, used in experiments, doesn't contain any double-Acting intensifiers, pressure drops obtained by single-Acting intensifier to perform simulated experiment. A die was designed and manufactured to synchronize the blank holder force with pressure drops. This die was integrated on the hydroforming press, located on Selcuk University Hydroforming Laboratory, for the success of the process. Performance of improved system was measured as well as repeatability of applying process parameters and product's geometry were determined. The AA5754 aluminum alloy used processes, both single-and double-Acting intensifier, were compared. Limiting drawing ratios were determined for all processes. It is obtained that pressure drops have no negative influence on formability. Moreover, there is no difference observed in thickness distribution which is an indicator of product's quality and strength. However, when geometric accuracy was investigated then noticed that the pressure drops count has a good influence on product radius. 5.96 mm product radiuses on the process with single-Acting intensifier was obtained 5.92 and 5.10 mm by using double-Acting intensifier increasing pressure drop's frequency. © The Authors, published by EDP Sciences, 2018., 16201043, This work is supported by the BAP office of Selcuk University with the project number 16201043 and Ermetal Otomotiv ve Eşya SanayiTicaret A.Ş.. Numerical verification and analysis studies are continuing in Ermetal Otomotiv ve Eşya Sanayi Ticaret A.Ş.. BAP support is profoundly acknowledged. This work has been extracted from Ahmet Can Günyadın’s M.Sc. thesis.

2nd International Conference on Mechanical, System and Control Engineering, ICMSC 2018 -- 21 June 2018 through 23 June 2018 -- -- 141803, Researches and studies on hydroforming process, which is a method that is getting more and more popular every day thanks to its many advantages in application, are ongoing. It is possible to pierce-the holes on a tube or sheet hydroformed part using hydropiercing method after the forming operation. In this study, hydropiercing process of a 304 stainless steel is simulated via the LS-Dyna in 2D axial symmetry model. In the simulations two types of punch movement was investigated to determine the contribution to the burr formation. In the simulations, Jonson-Cook hardening and damage model were used to determine the initiation of the crack on the samples. As a result, the burr formation can be eliminated by the two step movement of the punch through the piercing operation. © The Authors, published by EDP Sciences, 2018.

The performance of the ejector refrigeration system using ejectors with cylindrical mixing chamber is studied at operating conditions with choking in the mixing chamber. The condenser pressure is chosen so that the secondary flow choking can occur even in the ejector with the smallest area ratio. In the present study, the performance of the constructed system is determined by using six configurations of ejector and R-123 as working fluid in the system. The study is performed over a range of the ejector area ratio from 6.5 to 11.5 at the compression ratio 2.47. In the studied range, the experimental coefficient of performance of the system rises from 0.29 to 0.41, as the optimum generator temperature increases from 83 to 103 °C. Similar results were also found in the parametric study when the efficiencies of the nozzle and diffuser are taken as 0.90.

In this study, a method is proposed for dimensional measurements of semi-spherical parts for the standard tool electrodes used in Electrical Discharge Machining (EDM). The tool electrode to be measured is magnified by a profile projector. Pictures of some equatorial plane projections of the electrodes are captured by a digital camera before and after machining. The pictures were calibrated with the geometric camera calibration. Then, the profiles are extracted from their background using the adaptive threshold, which is an image processing method. 2D coordinates are first obtained and then converted to 3D coordinates. Using the obtained data, sphericity and radius are calculated by means of the minimum zone method. It is seen that the proposed method can be used for determining the EDM tool electrodes’ form error.

In this study, a hydroforming system was designed, built, and experimentally validated to perform lab-scale warm hydromechanical deep drawing (WHDD) tests and small-scale industrial production with all necessary heating, cooling, control and sealing systems. This manuscript describes the detailed design and fabrication stages of a warm hydroforming test and production system for the first time. In addition, performance of each subsystem is validated through repeated production and/or test runs as well as through part quality measurements. The sealing at high temperatures, the proper insulation and isolation of the press frame from the tooling and synchronized control had to be overcome. Furthermore, in the designed system, the flange area can be heated up to 400 °C using induction heaters in the die and blank holders (BH), whereas the punch can be cooled down to temperatures of around 10 °C. Validation and performance tests were performed to characterize the capacity and limits of the system. As a result of these tests, the fluid pressure, the blank holder force (BHF), the punch position and speed were fine-tuned independent of each other and the desired temperature distribution on the sheet metal was obtained by the heating and cooling systems. Thus, an expanded optimal process window was obtained to enable all or either of increased production/test speed, reduced energy usage and time. Consequently, this study is expected to provide other researchers and manufacturers with a set of design and process guidelines to develop similar systems.

WOS: 000332705200012, In this study, a new method is proposed to determine limit strains at the onset of localized necking for ductile materials that show post-uniform elongations. The new method is first applied for AA 5754-O using the ISO 12004-2 forming limit diagram determination standard. The method is also applied for ductile materials of 7114 steel, 304 stainless steel, and CuZn37 brass and finally for AA 2024-T4 having brittle fracture behavior. The results indicate that the new proposed method is quite successful, easy, and accurate for ductile materials that show post-uniform elongations., Scientific and Technological Research Council of Turkey (TUBITAK) [108M516]; TUBITAK-BIDEB; BAP office of Selcuk University, This work was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) (Project number: 108M516. Project Title: "Adding drawbead to the blank holder for enhancing formability of aluminum alloy sheets with hydroforming process''). Specifically Mevlut Turkoz would like to thank TUBITAK-BIDEB for financial support during his MSc studies. This work was also supported by the BAP office of Selcuk University. TUBITAK and BAP supports are profoundly acknowledged. This work has been extracted from Mevlut Turkoz's MSc thesis.

Tipik bir şekillendirme sınır eğrisi (ŞSE)’nde, minimum majör birim şekil değiştirme değeri, minör birim şekil değiştirme değerinin sıfır olduğu y ekseni üzerinde yer almaktadır. Birçok şekillendirme proseslerinde hasar bu bölgede meydana gelmektedir. Literatürde birçok çalışmada, ŞSE’lerde en düşük majör seviyesi hemen hemen y ekseni üzerinde elde edilmiştir. Bu çalışmada ise Al 2024-T4 alaşımı için bu değer, y ekseninden yaklaşık olarak 0,040 değerinde sağa doğru ötelenmiş olarak elde edilmiştir. Bu değer sac metal şekillendirme sonuçlarının değerlendirilmesinde önemli olabilmektedir. Bu çalışmada Al 2024-T4 sac metalin metalin minimum majör birim şekil değiştirme değerinin literatürden farklı olarak sağa ötelenmiş olarak elde edilmesinin nedenleri araştırılmıştır. Süzdürme çubuğu ve ısıl işlemin en fazla etki eden faktörler olduğu tespit edilmiştir. Ötelenmenin, süzdürme çubuğu kullanılarak yapılan testlerde oluşan ön BŞD’lerden ve T4 ısıl işlemi sonucunda meydana gelen kalıntı gerilmelerden kaynaklandığı gözlenmiştir., In a typical forming limit curve (FLC), the minimum major strain where the minor value is equal to zero is located at y axes. In many forming processes, failure occurs at this region. Many studies in literature indicates that minimum major strain value is obtained about at y axis. In this study, the minimum major strain value is not determined on the y axes and it was found to be offsetted from the y axes to the right about 0.04 strain for AA 2024-T4. This value could be important for evaluations of sheet metal forming processes. In this study, the reasons for the minimum major strain of setting of the forming limit curve for AA 2024-T4 were investigated. It was found that drawbead and heat treatment were most effective parameters for this offsetting. It is observed that offsetting result from pre-strain which occur for conducted tests with using draw-bead and residual stress arising from T4 heat treatment.

The deformation behavior of sheet materials changes according to temperature. It is possible that the formability of a material for different temperatures is investigated and the flow curves are obtained by using a hydraulic bulge test. Generally, biaxial stress state occurs in real forming processes. Flow curves can be derived from the hydraulic bulge test for the biaxial stress state, and the higher strain values can be achieved in comparison to the tensile test without extrapolation. Hydraulic bulge tests are preferred instead of tensile tests on account of presuming the problems can occur during the formation process of sheet material, being informed about the formability of material at the current pressure and temperature states, and obtaining flow curves to perform more accurate process simulations. In this study, the flow curves for the material AA5754-O were obtained using the warm bulge test and by considering the strain rates. The sections of the curves that can be used in simulation were identified, and these curves were comparatively investigated with respect to the curves obtained from the tensile test. In addition, case studies were performed in order to conduct more realisitic simulations using the results of the flow curves obtained from the bulge and tensile tests.

WOS: 000286212500010, Aluminum-magnesium (Al-Mg) alloys have been widely used in diverse applications ranging from automotive bodies to food processing industries because of their excellent high-strength-to-weight ratio, corrosion resistance, and recyclability potential. The formability of these alloys is decreased at room temperature (RT) and is related with the strain-rate sensitivity. This study presents the effect of strain-rate sensitivity on formability of AA 5754-O alloy sheet at a test temperature range of -60 to 250 A degrees C by duplicate tensile test at different strain rates. The test results indicated that the formability change with positive or negative strain-rate sensitivity values. It was observed that the strain-rate sensitivity values increased at negative temperatures with respect to RT. The best formability condition for this alloy in the test ranges was observed at 250 A degrees C and 0.0016 s(-1)., Scientific and Technological Research Council of Turkey (TUBITAK) [106M058], This work is supported by The Scientific and Technological Research Council of Turkey (TUBITAK). Project number: 106M058, Title: "Experimental and Theoretical Investigations of The Effects of Temperature and Deformation Speed on Formability." TUBITAK support is profoundly acknowledged.