Civil Engineering / İnşaat Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/13

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Department: search.filters.department.İzmir Institute of Technology. Mechanical EngineeringScopus Q: search.filters.scopusQuartile.N/A

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Now showing 1 - 7 of 7
  • Book Part
    Scherengestänge als elemente adaptiver morphologien
    (Birkhäuser, 2020) Akgün, Yenal; Maden, Feray; Gür, Şebnem; Kiper, Gökhan; Korkmaz, Koray; Aktaş, Engin; Yar Uncu, Müjde
    Zu allen Zeiten haben Menschen versucht, flexible Gebäude zu bauen, die sich ständig verändernden Anforderungen und Umweltbedingungen anpassen. Die Einbeziehung von Bewegung in die Architektur ist der Versuch, auf veränderliche Umstände mit neuen Lösungen zu reagieren. Das Konzept der Bewegung ist in der Tat nicht neu für die Architektur. Die Wurzeln gehen bis in die Antike zurück. Einfache, mit flexiblen Außenhäuten gebaute Nomadenzelte können als das erste Beispiel für adaptive Strukturen angesehen werden, die zum Schutz vor extremen Umweltbedingungen dienten.1 Die zum Abdecken des Daches im Colosseum von Rom verwendeten Leinwandbahnen sind ein weiteres Beispiel. Sie bildeten Markisen, die nicht nur Sonnenschutz boten, sondern für die Zuschauer durch ihr Durchhängen zur Mitte hin auch eine Brise einfingen.
  • Article
    Poliamid 6/6 (pa 66) Mikrofiberler ile Toklaştırılmış Tabakalı Kompozitlerin Mod-ı Delaminasyon Direncinin İstatiksel Analizi
    (Niğde Ömer Halisdemir Üniversitesi, 2019) Beylergil, Bertan; Tanoğlu, Metin; Aktaş, Engin
    Fiber takviyeli kompozitler, ağırlıklarına oranla yüksek mukavemet ve rijitlikleri nedeniyle uzay ve otomotiv yapısal parçalarında yaygın olarak kullanılmaktadır. Delaminasyon, bu kompozitlerde görülen en yaygın ve kritik hasar modudur. Bu kompozitlerin delaminasyon direncini arttırmak amacıyla, nanokatkılar ile epoksi toklaştırması, dikişleme, z-pimler ve arayüzeyde mikro/nanofiber kullanılması gibi pek çok sayıda teknik geliştirilmiştir. Bu çalışmada, poliamid 6/6 (PA 66) mikrofiberler ile toklaştırılmış karbon fiber/epoksi kompozitlerin Mode-I delaminasyon direnci Weibull dağılımı kullanılarak istatiksel olarak analiz edilmiştir. Test verilerinin istatiksel olarak değerlendirilmesi sonucunda PA 66 mikrofiberlerin kullanılmasının %90 güven seviyesinde kırılma tokluğunu yaklaşık %445 mertebesinde arttırdığı gözlemlenmiştir.
  • Conference Object
    Citation - Scopus: 1
    Development of Composite Drive Shaft Tube for Automotive Industry
    (Applied Mechanics Laboratory, 2019) Arslan Özgen, Gizem; Tanoğlu, Metin; Aktaş, Engin; Yücetürk, Kutay
    Weight, vibration, fatigue, and critical speed limitations have been recognized as serious problems in drive shafts in automotive industry for many years. Conventional drive shaft is made up into two parts to increase its fundamental natural bending frequency. This present work deals with the replacement of conventional steel drive shaft with a composite counterparts. The benefits of eliminating the two piece shafts are significant reductions in weight, noise, vibration and harshness. In this work, one-piece propeller shaft composed of carbon/epoxy and glass/epoxy composites have been designed and manufactured for a rear wheel drive automobile. The performance measures are static torque transmission capability, torsional buckling and the fundamental natural bending frequency. The tubular composite shaft samples are being manufactured by using filament winding technique. To predict the torsional properties, fatigue life and failure modes of composite tubes for different fiber orientation angle and stacking sequence, finite element analysis (FEA) has been used. The predicted and experimental values has been reported for comparison. The next phase of work consists of optimization of shaft for the objective function as weight and fundamental natural frequency considering different stacking sequence and fiber orientation. © CCM 2020 - 18th European Conference on Composite Materials. All rights reserved.
  • Book Part
    Scissor Linkages in the Design of Adaptive Morphologies
    (Walter de Gruyter GmbH, 2019) Akgün, Yenal; Maden, Feray; Gür, Şebnem; Kiper, Gökhan; Korkmaz, Koray; Aktaş, Engin; Yar Uncu, Müjde
    Scissor linkages are capable of forming various expandable structures. Architects can benefit from this type of linkage especially for designing adaptive, movable, transformable shell structures and deployable beam-like structures. Product designers may benefit as well. The two different methods described here convey the basic design approaches. The unit-based method is very effective for obtaining primary geometries like a dome, arch, circle or line, using serial multiplications and arrays of one of the scissor unit types presented here. The loop assembly method is more convenient when a final form, be it straight or free-form, is the main point of departure. In this case, unlike in the unit-based method, it is not necessary to opt for a specific scissor unit type and its dimensional constraints from the beginning. Designers can choose a type and number of loops and then define the scissor units following the loop sides. Since deployability is guaranteed by applying this method, the architect is free to choose the loop type most suitable for the functional needs and aesthetic concerns of the specific design. With the loop assembly method all loop alternatives can be assembled to scissor structures, their possible motions can be tested and evaluated in a short time, whereas the unit-based method is limited to a single type of motion that a specific unit can provide.
  • Article
    Citation - WoS: 31
    Citation - Scopus: 33
    Modification of Carbon Fibre/Epoxy Composites by Polyvinyl Alcohol (pva) Based Electrospun Nanofibres
    (Adcotec Ltd., 2016) Beylergil, Bertan; Tanoğlu, Metin; Aktaş, Engin
    In this study, the effects of modifying interlaminar region of unidirectional carbon fibre/epoxy composites by the incorporation of electrospun polyvinyl alcohol (PVA) nanofibres were investigated. PVA nanofibres were directly deposited onto the carbon fabrics by electrospinning method to improve mechanical performance of those composites. The features of the electrospun nanofibres were characterized by microscopy techniques. The unidirectional carbon fibre/epoxy composite laminates with/without PVA nanofibre interlayers were manufactured by vacuum-infusion technique in a [0]4 configuration. Tensile, three-point bending, compression, Charpy-impact and Mode-I fracture toughness tests (Double Cantilever Beam (DCB)) were carried out in accordance with ASTM standards to evaluate mechanical performance of the composites. Scanning electron microscopy (SEM) observations were made on the specimens to evaluate microstructural features. It was observed that the carbon fabrics were successfully coated with a thin layer of PVA nanofibres by electrospinning technique. The results showed that P VA nanofibres improve the mechanical properties of unidirectional carbon/epoxy composite laminates when subjected to in-plane loading. On the other hand, PVA nanofibres slightly reduced the mode-I fracture toughness values although they led to more stable crack propagation.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Trait-based heterogeneous populations plus (TbHP+) genetic algorithm
    (Elsevier Ltd., 2009) Tayfur, Gökmen; Sevil, Hakkı Erhan; Gezgin, Erkin; Özdemir, Serhan
    This study developed a variant of genetic algorithm (GA) model called the trait-based heterogeneous populations plus (TbHP+). The developed TbHP+ model employs a memory concept in the form of immunity and instinct to provide the populations with a more efficient guidance. Also, it has an ability to vary the number of individuals during the search process, thus allowing an automatic determination of the size of the population based on the individual qualities such as character fitness and credit for immunity. The algorithm was tested against the classical GA model in convergence and minimum error performance. For this purpose, 5 different mathematical functions from the literature were employed. The selected functions have different topological characteristics, ranging from simple convex curves with 2 variables to complex trigonometric ones having several hilly shapes with more than 2 variables. The developed model and the classical GA model were applied to finding the global minima of the functions. The comparison of the results revealed that the developed TbHP+ model outperformed the classical GA in faster convergence and minimum errors, which may be explained by the adaptive nature of the new paradigm.
  • Conference Object
    Citation - WoS: 1
    Citation - Scopus: 6
    Genetic Algorithm-Artificial Neural Network Model for the Prediction of Germanium Recovery From Zinc Plant Residues
    (Taylor and Francis Ltd., 2002) Akkurt, Sedat; Özdemir, Serhan; Tayfur, Gökmen
    A multi-layer, feed-forward, back-propagation learning algorithm was used as an artificial neural network (ANN) tool to predict the extraction of germanium from zinc plant residues by sulphuric acid leaching. A genetic algorithm (GA) was used for the selection of training and testing data and a GA-ANN model of the germanium leaching system was created on the basis of the training data. Testing of the model yielded good error levels (r2 = 0.95). The model was employed to predict the response of the system to different values of the factors that affect the recovery of germanium and the results facilitate selection of the experimental conditions in which the optimum recovery will be achieved.