Yazar "Kara, Emre" seçeneğine göre listele

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  • Küçük Resim
    Öğe
    Çeşitli elyaf dizilimleriyle oluşturulmuş metal köpük çekirdekli sandviç kompozitlerin mekanik davranışlarının incelenmesi
    (Hitit Üniversitesi Fen Bilimleri Enstitüsü, 2012) Kara, Emre; Aykul, Halil
    Sandviç kompozit üretimi ile elde edilen başarıların gün geçtikçe artması, bu tip malzemelere olan ilgiyi yoğunlaştırmıştır. Bu tezde, hafiflik ve mukavemet özelliklerinden dolayı tercih edilen sandviç kompozitler ve bu malzemelere yaygın olarak uygulanan mekanik test yöntemleri incelenmiştir. Bu çalışmanın amacı, yüzeyi çeşitli elyaf dizilimleriyle oluşturulmuş, alüminyum köpük ve alüminyum köpük sandviç (AKS) panel çekirdekli sandviç kompozitlerin mekanik davranışlarının deneysel olarak incelenmesidir.Sandviç kompozitlere yaygın olarak uygulanan mekanik test yöntemlerinden kenarına ve yüzeyine basma test yöntemleri, üç nokta eğilme test yöntemi ve düşük hızlı darbe test yöntemi uygulanmıştır. Her bir test yönteminin uygulama şekli ve test numuneleri gösterilerek, elde edilen grafikler sunulmuştur. Çalışmada, hafifliği yönüyle alüminyum köpük ve alüminyum köpük sandviç panel, çekirdek malzemeleri olarak kullanılmış ve bu köpükler hakkında detaylı bilgiler verilmiştir.Yapılan çalışmalar neticesinde sandviç kompozitlerin mevcut ağırlıklarına nazaran rijitlikleri ve mukavemetlerinin ne denli önemli olduğu gözlenmiştir. Benzer çalışmalarda kullanılan yüzey malzemeleri yerine bu çalışmada; tek eksenli dört kat [0o]2s, iki eksenli dört kat [0o/90o]2s, iki eksenli dört kat [45o/-45o] 2s, antisimetrik dizilimli iki eksenli dört kat [0o/90o]s/[45o/-45o]s ve simetrik dizilimli iki eksenli dört kat [0o/90o]s/[45o/-45o]s olmak üzere beş çeşit elyaf dizilimiyle cam elyaf malzemeleri epoksi reçine emdirilerek Cam Elyaf Takviyeli Plastik (CTP) oluşturulmuş ve CTP, bu epoksi reçine vasıtasıyla çekirdek malzemesi olan alüminyum köpüğe yapıştırılmıştır. Alüminyum köpük sandviç panel çekirdekli kompozitler için ise iki kat [0o/90o/Mat]s dizilimli cam elyaf ve farklı bir epoksi reçine kullanılarak CTP oluşturulmuş ve aynı reçine ile çekirdek malzemesine yapıştırılmıştır.Basma ve eğilme test yöntemleri sonucunda, farklı oryantasyon açılarında elde edilen gerilme-%uzama ve yük-sehim eğrileri ile düşük hızlı darbe deneyi sonucunda farklı hızlarda elde edilen yük-zaman ve yük-uzama eğrileri karşılaştırmalı olarak sunulmuştur.
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    Öğe
    Computed tomography analysis of impact response of lightweight sandwich panels with micro lattice core
    (SAGE Publications Ltd, 2018) Abrate, Serge; Epasto, Gabriella; Kara, Emre; Crupi, Vincenzo; Guglielmino, Eugenio; Aykul, Halil
    One of the main focuses in transportation engineering is the application of sandwich materials in order to create safer and efficient vehicles. The main focus of this study was the application of 3D computed tomography for analyzing the responses of sandwich panels with micro lattice core subjected to impact loading. Micro lattice specimens were manufactured using Ti-6Al-4V powder by means of a direct metal laser sintering system. A theoretical model was applied for predicting the failure initiation loads under impact loading. The predictions presented good consistency with the experimental measurements. The 3D computed tomography system was used for the analysis of the collapse modes of the micro lattice sandwich panels after low-velocity impact tests. Experimental and theoretical results proved that lightweight sandwich panels with micro lattice cores are excellent energy absorbers and, therefore, they could have significant applications in the transportation industry. © 2018, © IMechE 2018.
  • Küçük Resim
    Öğe
    Engelli bireylerde motor beceri
    (Hitit Üniversitesi Lisansüstü Eğitim Enstitüsü, 2022) Kara, Emre; Çeviker, Abdulkerim
    Günümüze kadar yapılan çalışmalar incelendiğinde engelli bireylerde motor beceri üzerine çalışma sayısı yeterli düzeyde olmadığı görülmektedir. Bu nedenle engelli bireylerde motor beceri üzerindeki bilimsel olarak açıklanamamıştır. Engelli bireylerde motor beceri üzerine yapılmış çalışmalar incelendiğinde sistematik bir derlemeye rastlanmamıştır. Bu çalışma, engelli bireylerde motor becerinin etkisi ve önemini konusu üzerine yayınlanmış bilimsel çalışmaların sistematik derlemesidir. Konuyla ilgili olarak sistematik derleme yapılırken güncel bilimsel çalışmaların taraması yapılmıştır. Bu tez, sistematik derleme, PRISMA (Preferred Reporting Items for Systematic review and Meta-Analysis) bildirgesine uyarak ortaya konmuştur. Bedensel, Görme, Zihinsel ve İşitme Engelliler gruplarının dışında kalan engel grupları çalışmaya dahil edilmemiştir. PubMed veri tabanında '(motor skill) AND (disabled)" anahtar kelimeleri ile yapılan aramada toplam 3,116 yayın tespit edildi. "Ücretsiz tam metin" sınırlaması yapıldığında sayı 2100'e düşmüş "Randomize-Kontrollü çalışma" ve ''Deneysel Araştırma'' "Review" sınırlamaları eklendikten sonra yapılan aramada toplam 256 sonuç elde edilmiştir. İnsan üzerinde yapılan çalışmalar ve yaş kriteri de dahil edildiğinde sayı 110' a düştü. Bunlardan 90 tane bilimsel çalışma konu dışı olması sebebiyle dışarıda bırakıldı. Geri kalan 20 yayın çalışmaya dahil edilmiştir. Çalışma sonuçlarına bakıldığında; engelli bireylerde gelişim sürecinin ilk üç yılında motor gelişimin bilişsel gelişim ile ilişki içinde olduğu görülmektedir. Spora katılan ve katılmayan engelli ilkokul çocuklarında motor performans ölçümü sonucunda ve spora katılan çocukların, katılmayan çocuklara kıyasla daha iyi motor performansı gösterdikleri görülmektedir. Engelli bireylerde motor beceri gelişiminin erken tanısının konulması ve motor becerilerde geriliği tespit edilen engelli bireylerde erken eğitim ve egzersiz müdahalelerinin önemli olduğu çalışmamız sonucunda önerilebilir.
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    Fatigue behavior of adhesively bonded glass fiber reinforced plastic composites with different overlap lengths
    (SAGE Publications Ltd, 2015) Kara, Emre; Kurşun, Ali; Haboğlu, Mustafa Reşit; Enginsoy, Halil Murat; Aykul, Halil
    The joining techniques of lightweight and strong materials in the transport industry (e.g. automotive, aerospace, shipbuilding industries) are very important for the safety of the entire structure. In these industries, when compared with other joining methods, the use of adhesively bonded joints presents unique properties such as greater strength, design flexibility, and reduction in fuel consumption, all thanks to low weight. The aim of this study was the analysis of the tensile fatigue behavior of adhesively bonded glass fiber/epoxy laminated composite single-lap joints with three different specimen types including 30, 40 and 50mm overlap lengths. In this study, composite adherents were manufactured via vacuum-assisted resin transfer molding and were bonded using Loctite 9461A&B toughened epoxy adhesive. The effect of a surface treatment method on the bonding strength was considered and it led to an increment of about 40%. A numerical analysis based on a finite element model was performed to predict fatigue life curve, and the predicted results showed good agreement with the experimental investigation. © IMechE 2015.
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    Öğe
    Flexural behaviour of glass fiber reinforced aluminium honeycomb sandwiches in flatwise and edgewise positions
    (European Conference on Composite Materials, ECCM, 2014) Kara, Emre; Crupi, Vincenzo; Epasto, Gabriella; Guglielmino, Eugenio; Aykul, Halil
    The goal of this research was the analysis of edgewise bending response of sandwiches, which consists of aluminium honeycomb sandwich reinforced by outer skins made of glass fiber reinforced epoxy matrix. The test results at different values of support span distances in terms of peak loads and absorbed energy were compared with those obtained by flatwise bending tests and by similar tests on aluminium honeycomb sandwiches without outer skins. The failure mechanisms have been also investigated. The experimental results presented that the sandwiches in the edgewise position failed at a higher load with less deflection compared to the specimens tested in the flatwise position. The current work has an important role in several areas, such as transport industry, in which lightweight structures with high capacity of energy dissipation is required.
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    Öğe
    Impact response of sandwiches with open-cell casting metal foam and GFRP skins
    (Taylor and Francis Ltd., 2016) Kurşun, Ali; Kara, Emre; Aykul, Halil; Şenel, Mehmet; Ağır, İnan
    The main advantage of using sandwich structures is their high strength, high energy absorbing capacity and high bending stiffness to weight ratio. Therefore, they are unique for the applications where the light-weight design philosophy is a crucial aspect. While sandwich structures with polymeric foams have been applied for many years, recently there is a growing interest on a new generation composite sandwiches with metallic foam core. In this study, the influence of pores per inch (ppi) of the foam on low-velocity impact response of the entire panel has been investigated. The glass fibre reinforced plastic (GFRP) skins produced by vacuum bagging technique in the study were easily bonded to the foam surfaces using a commercial adhesive in order to combine the composite sandwich panel. The low-velocity impact tests are performed to the sandwiches with the combination of two different magnesium (Mg) alloy foams (having 10 pores per inch (ppi) and 20 pores per inch), and carried out by a drop test machine with different values of impact velocity ranging from 1 to 10 m/s in order to analyse its effect. The main results of the impact tests are: force-displacement curves, peak force values, absorbed energy and influence of impact velocity. © 2016, © 2016 Informa UK Limited, trading as Taylor & Francis Group.
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    Investigation of the effect of temperature on the mechanical properties of E-Glass fiber reinforced composites
    (The Composites and Advanced Materials Expo (CAMX), 2014) Haboğlu, Mustafa Reşit; Kurşun, Ali; Kara, Emre; Çetin, Erhan; Aykul, Halil
    In this study, mechanical characterization of E-Glass fiber reinforced composite materials that are manufactured via Vacuum Infusion (VI) (a.k.a Vacuum Assisted Resin Transfer Molding (VARTM)) is investigated. The mechanical properties are analyzed at different temperatures (23 oC (room temperature), 40 °C, 60 °C, 80 °C, 100 °C) by using a universal tensile testing machine integrated with a heat chamber. The mechanical tests are performed for 3 different reinforcement types such as (i) plain woven, (ii) biaxial stiched and (iii) quadraxial stiched E-Glass fabrics. The result of this study provides a database for applications that use composite materials at different temperatures.
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    Öğe
    Low velocity impact response of glass fiber reinforced aluminium foam sandwich
    (European Conference on Composite Materials, ECCM, 2012) Kara, Emre; Crupi, Vincenzo; Epasto, Gabriella; Guglielmino, Eugenio; Aykul, Halil
    The aim of this study was the analysis of the bending and the low - velocity impact response of aluminium foam sandwich reinforced by the outer skins made of glass fiber reinforced epoxy matrix and the results were compared with those obtained for aluminium foam sandwiches without glass fiber skins. Static bending tests were carried on panels with the same nominal size at different support span distances in order to analyze the collapse modes and their capacity of absorbing energy, while the energy amount absorbed under dynamic loading was evaluated by means of impact tests. The experimental investigation has particular importance for applications which require lightweight structures with a high capacity of energy dissipation, such as transport industries.
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    Öğe
    Prediction model for the impact response of glass fibre reinforced aluminium foam sandwiches
    (Elsevier Ltd, 2015) Crupi, Vincenzo; Kara, Emre; Epasto, Gabriella; Guglielmino, Eugenio; Aykul, Halil
    The use of sandwich structures combines low weight with high energy absorbing capacity, so they are suitable for applications in the transport industry (automotive, aerospace, shipbuilding industry), where the "lightweight design" philosophy and the safety of vehicles are very important aspects. The goal of this paper was the analysis of the bending and the low - velocity impact response of aluminium foam sandwiches reinforced by the outer skins made of glass fibre reinforced epoxy matrix. The results were compared with those obtained for aluminium foam sandwiches without glass fibre skins. An analytical model for the peak load prediction under low velocity impact was developed and the predicted values are in good agreement with the experimental measurements. The impact response of the sandwiches was investigated using a theoretical approach, based on the energy balance model and the model parameters were obtained by the tomographic analyses of the impacted panels. This combined experimental and theoretical investigation has particular importance for applications that require lightweight composite structures with a high capacity of energy dissipation, such as the transport industry, where problems of collision and crash have increased in the last years. © 2014 Elsevier Ltd. All rights reserved.
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    Static behavior of lattice structures produced via direct metal laser sintering technology
    (Elsevier Ltd, 2017) Crupi, Vincenzo; Kara, Emre; Epasto, Gabriella; Guglielmino, Eugenio; Aykul, Halil
    The aim of this scientific work was the analysis of the micro lattice structures under uniaxial quasi-static compression loading with regard to the effect of unit cell size and strut diameter. A wide range of cubic lattice blocks designed in a CAD software were fabricated using Ti6Al4V (Ti64) metal powder and two different production parameters in the direct metal laser sintering machine. The failure modes of the specimens were investigated and the 3D Computed Tomography system was used for the morphological analysis of the struts. An analytical model, developed by Gibson and Ashby, was adapted to the titanium body centered cubic lattices in order to predict their mechanical properties for compressive loading. Moreover, the compressive responses of the lattice structures were also studied using a numerical approach based on finite element analysis. Both experimental and theoretical results presented good agreement in terms of mechanical properties of the body centered cubic lattices and showed that such structures are great energy absorbers. Theoretical approaches gave significant results on the predictions of mechanical properties of these cellular structures, which are suitable for biomedical and transport engineering applications, in order to save manufacturing cost and time. © 2017 Elsevier Ltd
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    Theoretical and experimental analysis for the impact response of glass fibre reinforced aluminium honeycomb sandwiches
    (SAGE Publications Ltd, 2018) Crupi, Vincenzo; Kara, Emre; Epasto, Gabriella; Guglielmino, Eugenio; Aykul, Halil
    Honeycomb sandwich structures are increasingly used in the automotive, aerospace and shipbuilding industries where fuel savings, increase in load carrying capacity, vehicle safety and decrease in gas emissions are very important aspects. The aim of this study was to develop the theoretical methods, initially proposed by the authors and by other researchers for the prediction of low-velocity impact responses of sandwich structures. The developed methods were applied to sandwich structures with aluminium honeycomb cores and glass-epoxy facings for the assessment of impact parameters and for the prediction of limit loads. The values of model parameters were compared with data reported in literature and the predictions of the limit loads were validated by means of the experimental data. Good achievement was obtained between the results of the theoretical models and the experimental data. The failure mode and the internal damage of the sandwich panels have been investigated using 3D computed tomography, which allowed the evaluation of parameters of energy balance model, and infrared thermography, which allowed the detection of the temperature evolution of the specimens during the tests. The experimental and theoretical results demonstrated that the use of glass-epoxy reinforcement on aluminium honeycomb sandwiches enhances the energy absorption and load carrying capacities. © 2016, © The Author(s) 2016.