Özdemir, İzzet
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Name Variants
Ozdemir,I.
O., Izzet
Izzet, Ozdemir
İzzet, Özdemir
Ö.,İzzet
O.,Izzet
Özdemir, İzzet
I.,Ozdemir
I., Ozdemir
İ.,Özdemir
Ozdemir, Izzet
Özdemir,İ.
Ozdemir, I.
O., Izzet
Izzet, Ozdemir
İzzet, Özdemir
Ö.,İzzet
O.,Izzet
Özdemir, İzzet
I.,Ozdemir
I., Ozdemir
İ.,Özdemir
Ozdemir, Izzet
Özdemir,İ.
Ozdemir, I.
Job Title
Doktor Öğretim Üyesi
Email Address
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Scholarly Output
9
Articles
6
Citation Count
128
Supervised Theses
1
8 results
Scholarly Output Search Results
Now showing 1 - 8 of 8
Article Citation Count: 9Grain statistics induced size effect in the expansion of metallic micro rings(Pergamon-elsevier Science Ltd, 2014) Özdemir, İzzet; Manufacturing EngineeringThis study focuses on the expansion of metallic micro rings under internal pressure using a grain level three dimensional finite element analysis in combination with a rate dependent crystal plasticity constitutive model. The size effect due to grain statistics such as grain orientations and number of grains through the thickness is investigated to a certain depth, in terms of final geometries and the scatter involved. The findings of the study could be used as the preliminary guidelines for suitable material selection in stretching dominated microforming operations. (C) 2014 Elsevier Ltd. All rights reserved.Article Citation Count: 19Modeling thermal shock damage in refractory materials via direct numerical simulation (DNS)(Elsevier Sci Ltd, 2010) Özdemir, İzzet; Brekelmans, W. A. M.; Geers, M. G. D.; Manufacturing EngineeringIn this paper, a computational investigation on thermo-mechanically induced damage in refractory materials resulting from severe thermal shock conditions is presented. On the basis of an idealized two-phase material system. molten aluminium thermal shock tests' are computationally modeled by means of direct numerical simulations (DNS) The interfacial and bulk damage evolution within the material arc described by Merino-mechanical cohesive zones and continuum damage mechanics (CDM), respectively Reported experimental results' are used to identify the parameters of the model Furthermore, a parametric study is carried out to investigate the relative significance of various microstructure parameters in the context of thermal shock response. (C) 2009 Elsevier Ltd All rights reservedArticle Citation Count: 3Predicting and Measuring Surface Enlargement in Forward Rod Extrusion(Asme, 2016) Özdemir, İzzet; Ozdemir, Izzet; Manufacturing EngineeringSurface enlargement during bulk metal forming processes is one of the key parameters controlling the tribology at the tool-workpiece interface. Not only the surface roughness evolution but also the integrity of the lubricant layer critically reposes on surface enlargement. As an attempt to address this issue, in the first part of this work, a general, deformation gradient based surface enlargement description is implemented in a commercial finite element program. In the second part, forward rod extrusion tests with different area reductions are conducted using customized steel workpieces in which cylindrical copper rods are embedded through the depth. By sectioning the extruded parts and by identifying the position of the copper rods on the lateral surface, average surface enlargement values could be measured locally at different positions along the extrudate. Comparison of experiments and numerical predictions reveal that the deformation gradient based description performs reasonably well in capturing surface enlargement profiles both qualitatively and quantitatively.Conference Object Citation Count: 0On the importance of thermo-mechanical modelling of the double cup extrusion test(Trans Tech Publications Ltd, 2014) Karadoğan, Celalettin; Özdemir, İzzet; Ozdemir,I.; Manufacturing EngineeringFinding the correct friction coefficient for the simulation of bulk metal forming processes is crucial. The practical approach nowadays for this objective is to conduct a friction sensitive process-test and the corresponding numerical simulation in order to reveal the friction coefficient. The Double Cup Extrusion Test (DCET) is one of the widely used friction tests for bulk metal forming. Although, there is a large body of literature on DCETs, there are still important aspects which have not been addressed yet. Motivated by this fact, this study emphasizes and demonstrates the importance of thermo-mechanical modelling to evaluate the DCET for the characterization of friction coefficients even for cold forging processes. To this end, thermo-mechanical material characterization covering necessary temperature and strain rate spectrum is conducted and used in the thermo-mechanically coupled finite element analysis (FEA) of the DCET. These findings are compared with the results of single flow curve based purely mechanical FEA in terms of cup height ratios as well as force-displacement curves for two different press speeds. © (2014) Trans Tech Publications, Switzerland.Article Citation Count: 7Topological derivative based optimization of 3D porous elastic microstructures(Elsevier Science Bv, 2014) Özdemir, İzzet; Manufacturing EngineeringAs an alternative to the well established microstructural optimization techniques, topological derivative based optimization framework has been proposed and successfully implemented for tailoring/optimizing 2D elastic composites recently, Amstutz et al. [1]. In this paper, an optimization framework for 3D porous elastic microstructures is presented which is based on the notion of topological derivative and the computational homogenization of elastic composites. The sensitivity of the homogenized elasticity tensor to the insertion of infinitesimal hollow spheres within the elastic microstructure is used as the measure for the finite element based evolutionary optimization algorithm. The capabilities of the proposed framework, which is free of any regularization parameter, is assessed by means of example problems including some comparisons with analytical bounds. (C) 2013 Elsevier B.V. All rights reserved.Article Citation Count: 56A Thermo-mechanical cohesive zone model(Springer, 2010) Özdemir, İzzet; Brekelmans, W. A. M.; Geers, M. G. D.; Manufacturing EngineeringIn this paper, a cohesive zone formulation that is suitable for the thermo-mechanical analysis of heterogeneous solids and structural systems with contacting/interacting components, is presented. Well established traction-opening relations are adopted and combined with micromechanically motivated heat flux-opening relations reflecting the evolving heat transfer through the interfaces. The finite element approach for a coupled analysis within an operator-split solution framework is presented and demonstrated with an example problem.Master Thesis Mikro-ekstrüzyon işlemi üzerine deneysel-sayısal bir inceleme(2013) Özdemir, İzzet; Özdemir, İzzet; Şengönül, Merih; Manufacturing EngineeringBu çalışmada, mikro şekillendirme işlemleri ile ilgili bir anlayış geliştirebilmek için mikro ekstrüzyon üzerine deneysel ve sayısal araştırmaları içeren bir çalışma sunulmaktadır. Deneysel tarafta; istatiktiksel boyut etkisini göstermek için bir dizi mikro ekstrüzyon deney düzeneği hazırlanmış, farklı ,ortalama tanecik büyüklüklüğüne sahip bakır çubuklar kullanılarak mikro ekstrüzyon testleri başarıyla gerçekleştirilmiştir. Modelleme kısmında ise, şekillendirme boyunca oluşan büyük yerdeğiştirme-büyük gerinimler dikkate alınarak, geometrik olarak lineer olmayan sürekli ortamlar mekaniği tercih edilmiştir. Mikro şekillendirme süreçlerinde tanecik büyüklüğü seviyesinin tanımlanması gerekliliğinden dolayı Kristal Plastisite teorisi mekanik davranışın modellenmesinde kullanılmıştır. Bu amaçla Kristal Plastisite teorisine bağlı kullanıcı tanımlı malzeme modeli kodlanarak Sonlu Elemanlar Analiz Programı ``Abaqus'' içine entegre edilmiştir. Bu şekilde küçük ölçeklerde tanecik yönelimlerinin sürtünme parametresi üzerine olan etkisi sayısal olarak incelenmiştir.Article Citation Count: 34Modeling of dislocation-grain boundary interactions in a strain gradient crystal plasticity framework(Springer, 2014) Özdemir, İzzet; Yalcinkaya, Tuncay; Manufacturing EngineeringThis paper focuses on the continuum scale modeling of dislocation-grain boundary interactions and enriches a particular strain gradient crystal plasticity formulation (convex counter-part of Yal double dagger inkaya et al., J Mech Phys Solids 59:1-17, 2011; Int J Solids Struct 49:2625-2636, 2012) by incorporating explicitly the effect of grain boundaries on the plastic slip evolution. Within the framework of continuum thermodynamics, a consistent extension of the model is presented and a potential type non-dissipative grain boundary description in terms of grain boundary Burgers tensor (see e.g. Gurtin, J Mech Phys Solids 56:640-662, 2008) is proposed. A fully coupled finite element solution algorithm is built-up in which both the displacement and plastic slips are considered as primary variables. For the treatment of grain boundaries within the solution algorithm, an interface element is formulated. The proposed formulation is capable of capturing the effect of misorientation of neighboring grains and the orientation of the grain boundaries on slip evolution in a natural way, as demonstrated by bicrystal specimen examples.
