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2. Üç boyutlu ve iki boyutlu eleman tiplerinin punta kaynaklı bileşenlerin gerilme ve ömür analizleri üzerindeki etkisi.
- Author
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DURAN, Ertuğrul Tolga
- Subjects
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HIGH cycle fatigue , *SPOT welding , *STRAINS & stresses (Mechanics) , *METHODS engineering , *FINITE element method , *DYNAMIC loads - Abstract
Finite element analysis and computer-aided engineering methods have an essential role in modern research and development projects. Although proper element selection for the modeling type is critical for the accuracy of simulations, the selection process might be difficult for researchers in some cases where geometric conditions are challenging. The main objective of this paper is to present the differences in simulation results when three-dimensional cubic and two-dimensional quadrilateral elements are used for the modeling of spot-welded components. Following the modeling of shear specimens having two spot welds with different element types, static analysis, and high cycle fatigue simulations at three different dynamic load cases have been run within the context of this study. Displacement, stress values and tensors, as well as high cycle fatigue life have been evaluated as the output of analysis, and deviations due to different element types have been reported. Accuracy levels of different element types have been determined by comparing the life obtained by simulations with high cycle fatigue tests. The studies conducted within the content of this paper indicate that the rigid spot weld modeling with two dimensional quadrilateral elements give better consistency with the fatigue tests in comparison with the modeling with three dimensional cubical elements. The modeling procedures of correlated high cycle fatigue simulations have been detailed for spot welding, which is one of the most applied methods in aviation, automotive and marine industry. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
3. Hava araçlarında kablolamada kablo düzeninin, kablolar arası uzaklığın ve ortam sıcaklığının kablo akım taşıma kapasitesine etkisinin sonlu elemanlar yöntemi ile çoklu fiziksel analizi
- Author
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Yıldız, Burhan Mert, Kalenderli, Özcan, and Altay, Özkan
- Subjects
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FINITE element method , *CABLE-stayed bridges , *CABLES , *THERMAL analysis - Abstract
In this paper, in order to determine the laying conditions of power cables used in air vehicles, the thermal behavior, which is one of the dominant factors affecting the current carrying capacity, was investigated by the finite element method. For this purpose, electrical-thermal multiple physical analysis model was created in COMSOL programme to observe the relationship between the temperature of the cable and the environment in which it is laid and the current carrying capacity. In the analysis, 2 AWG (39.19 mm2) cross-section cables in accordance with SAE AS22759/1 standard were taken into consideration. Within the scope of the study, the effect of both the ambient temperature and the distance between the cables on the current carrying capacity of the cable was examined. Considering the maximum temperature value (200℃) that the selected cables can withstand, while there is a distance of 75 mm between the cables it has been observed 198A for a cable. When the distance between the cables is 30 mm and the cables are adjacent, current values are as 184A and 181A, respectively. When the cables are in adjacent, analysis was performed for ambient temperature values of 70℃, 50℃ and 20℃. According to these ambient temperature values, current carrying capacity is calculated as 179A, 191,5A and 205A respectively. As a result of the analysis, the decrease in the distance between the cables causes the current carrying capacity of the cable to decrease and it has been observed that the decrease in the ambient temperature also causes the current carrying capacity of the cable to increase. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. HAVA ARAÇLARI İÇİN DEĞİŞKEN AKILI RELÜKTANS GENERATÖR TASARIMI.
- Author
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GÜRLEYEN, Hilmi
- Subjects
ELECTRIC power production ,HARMONIC analysis (Mathematics) ,HYBRID electric airplanes ,FINITE element method ,ELECTRIC inductance - Abstract
Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2023
- Full Text
- View/download PDF
5. ARDGERMELİ BETONARME KÖPRÜ TABLİYESİNDE HALAT YERLEŞİMİNİN İRDELEMESİ VE EKONOMİK DEĞERLENDİRMELER.
- Author
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TURAN, Mustafa
- Subjects
HIGH strength concrete ,POST-tensioned prestressed concrete ,TENDONS (Prestressed concrete) ,FINITE element method ,BRIDGE floors ,CONCRETE bridges ,PRESTRESSED concrete beams ,PRESTRESSED concrete - Abstract
Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2020
- Full Text
- View/download PDF
6. Kendi ağırlığının dairesel delik içeren eğilme altındaki öngerilmeli şerit-plağın dinamik analizine etkisi.
- Author
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Yeşil, Ülkü Babuşcu
- Subjects
- *
BOUNDARY value problems , *SURFACE forces , *ELASTICITY , *PROBLEM solving , *HOLES - Abstract
This paper investigates the effect of own weight on the dynamic analysis of a pre-stretched composite platestrip containing a circular hole subjected to bending load. The combined effect of body forces (weight) and surface forces (pre-stretching load) on the plate-strip with a hole is considered as the initial stresses determined within the linear theory of elasticity. The effects of these initial stresses on the natural and forced vibrations around the hole within a plate-strip under additional bending load are investigated in the framework of the Three-Dimensional Linearized Theory of Elasticity (TDLTE) under the plane strain state, and the solutions of the considered boundary value problems are solved numerically by using the finite elements method. This paper shows that the influence of the plate's own weight has an important role on the dynamic analysis around the circular hole within a plate-strip. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
7. Silis dumanının geri kazanılmış agregalı beton kırılma parametreleri ve çatlak haritası üzerine etkisi.
- Author
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Çakır, Özgür and Dilbas, Hasan
- Subjects
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CRACKS in reinforced concrete , *CONCRETE beams , *CONCRETE fractures , *SILICA fume , *FINITE element method , *WOODEN beams - Abstract
The paper demonstrates the determination of the fracture parameters of concretes included recycled aggregate (RA) and silica fume (SF) and the crack pattern of a reinforced concrete beam. Double-K fracture model (DKFM) is considered in this paper and the required parameters for DKFM are obtained from the model simulated using finite element method (FEM) in Abaqus. In the simulation parts geometric nonlinearity and material nonlinearity is considered and the parameters of materials for modelling applications depends on the experiments. The fracture parameters are calculated after obtaining the FEM model analyses. The implemented study of fracture behavior of the conventional and recycled aggregate concretes with and without SF and RA reveals that the conventional concrete fracture models (double-K fracture model) could be used to determine the fracture parameters and fracture behavior of RAC and both SF and RA use in concrete has an effect on fracture properties is found. Moreover, crack pattern of a reinforced concrete beam with and without RA and SF is investigated. According to the results, number of cracks decrease but the depth of cracks increase and initial cracking toughness increases if both RA and SF are used at various ratios in the concretes. Although RA inclusion in concretes decreases the rigidity of the beam, approximately equal elastic bearing capacity of the beam is found. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
8. Kendi ağırlığının dairesel delik içeren eğilme altındaki öngerilmeli şeritplağın dinamik analizine etkisi.
- Author
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Yeşil, Ülkü Babuşcu
- Abstract
This paper investigates the effect of own weight on the dynamic analysis of a pre-stretched composite plate-strip containing a circular hole subjected to bending load. The combined effect of body forces (weight) and surface forces (pre-stretching load) on the plate-strip with a hole is considered as the initial stresses determined within the linear theory of elasticity. The effects of these initial stresses on the natural and forced vibrations around the hole within a plate-strip under additional bending load are investigated in the framework of the Three-Dimensional Linearized Theory of Elasticity (TDLTE) under the plane strain state, and the solutions of the considered boundary value problems are solved numerically by using the finite elements method. This paper shows that the influence of the plate's own weight has an important role on the dynamic analysis around the circular hole within a plate-strip. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
9. Frenli tas menteşe kinematik, kinetik ve yorulma analizi.
- Author
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Bayraktar, Meral, Bilyaz, Hidayet, and Demir, Cihan
- Abstract
Copyright of Sakarya University Journal of Science (SAUJS) / Sakarya Üniversitesi Fen Bilimleri Enstitüsü Dergisi is the property of Sakarya University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2018
- Full Text
- View/download PDF
10. YAPAY ZEKA KULLANILARAK TREN TEKERLEKLERİNİN YORULMA ÖZELLİKLERİNİN VEKİL MODELLENMESİ.
- Author
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MAHOUTİ, Mehran, KÖMEK, Mehmed Sinan, and YILMAZ, Suat
- Abstract
Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2024
- Full Text
- View/download PDF
11. Tarihi Başdurak Camisinin deprem analizi.
- Author
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USTA, Pınar and BOZDAĞ, Özgür
- Subjects
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MONUMENTS , *FINITE element method , *HISTORIC preservation , *PRESERVATION of monuments , *CULTURAL property , *EARTHQUAKE resistant design - Abstract
Masonry historical monuments that connecting the past and the present are of major importance in terms of reflecting the knowledge and property of different cultures. This explains that why the protection of historic monuments is so important. The preservation of the historical monuments that constitute our historical and cultural heritage is only possible if they are examined in detail, their problems are solved and their solution methods and techniques are improved. One historical masonry mosque was selected to study in this paper. The mosque is modeled and analyzed by using SAP2000 finite element software in accordance with the dimensions of an architectural building survey. Seismic assessment of the monument was carried out via three-dimensional time-history dynamic analyses of the structure. Minimum and maximum values of displacements, base shear, and stress were interpreted, and the results were displayed graphically and discussed the earthquake motion was applied in two different directions which is X and Y. The seismic capacity of this building has been determined for varied earthquake grade. As a result of the analysis, displacements, stresses (tensile and compressive), base shear force were calculated under the effect of earthquakes. The Structural safety of the mosque was evaluated, and three-dimensional finite element analysis gave a general idea about the structural performance of the mosque. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
12. Üç Sıkıştırılabilir Malzemeden Yapılmış Ön Gerilmeli Bir Plakanın Frekans Tepkisi.
- Author
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DAŞDEMİR, Ahmet
- Abstract
Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2021
- Full Text
- View/download PDF
13. Halbach dizilimi ve PSO algoritması kullanarak DMSM'nin geometrik en iyilemesi.
- Author
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Soygenç, Osman Can and Ergene, Lale T.
- Subjects
- *
PERMANENT magnet motors , *PARTICLE swarm optimization , *FINITE element method , *MATHEMATICAL optimization , *GENETIC algorithms , *MAGNETS , *INTERIOR architecture - Abstract
Most studies on permanent magnet synchronous motors (PMSMs) focus on either interior type or surface mounted magnet configurations and their design changes. This paper deals with the improvements on PMSMs' efficiency and performance after Halbach Array implementation by using meta-heuristic optimization algorithms. Analytical and numerical modeling of the motor are achieved and finite element method (FEM) is used for the numerical models. Particle swarm optimization & genetic algorithm were performed for the optimal design of the geometrical parameters of the permanent magnet (PM). The analytical and numerical results of the proposed design are compared to the analytical and/or numerical results of the reference motor. The improvements in efficiency, power/weight ratio, and cost are achieved with the optimized motor structure for the same motor requirements. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
14. Kuş Çarpmaları ve Uçaklara Etkileri Üzerine Bir Gözden Geçirme Çalışması.
- Author
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Gülcan, Orhan
- Subjects
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FINITE element method , *FOREIGN bodies , *AERONAUTICAL safety measures , *MOTORS , *NUMERICAL analysis , *FLIGHT simulators , *AIRCRAFT fuels - Abstract
Bird strike is a significant threat to aviation safety. Of all foreign object damages to aircraft, 90 % can be attributed to the bird strikes. Most bird strikes are occurred when an aircraft is at a low altitude during take-off and landing phases of a flight. To ensure flight safety, aviation regulations require a certain level of bird strike resistance for critical components (windward components such as nose, windshield, motor engine inlet, wing or tail leading edges). To meet these regulations, both bird strike tests are conducted experimentally and also analyses based on numerical simulation are made in computer environment due to expensiveness of these tests. Choosing the proper parameters in the tests and the analyses is very important in order to be able to pre-determine the damage following a real bird strike event and to design related components in accordance with these parameters. This paper reviews theoretical background, the finite element analyses (based on substitute bird materials, bird modelling methods, bird geometry) and related tests about bird strike problem. [ABSTRACT FROM AUTHOR]
- Published
- 2019
15. STATIC ANALYSES OF THE EFFECT OF DEEP EXCAVATION ON THE BEHAVIOUR OF AN ADJACENT PILE IN SAND
- Author
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Yeşim S. Ünsever and Sameh Ashour
- Subjects
derin kazı ,tekil kazık ,kum zemin ,sonlu elemanlar yöntemi ,deep excavation ,single pile ,finite element method ,sand ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The influence of deep excavation on adjacent pile behaviour is an important issue to ensure its serviceability and stability. In this paper, the effect of deep excavation on an adjacent loaded single pile in saturated cohesionless soil was investigated by 3D finite element method. After verification of finite element model using centrifuge test results found in literature, a parametric study was conducted by varying the most influence factors on the pile behaviour such as excavation depth, distance from the pile to the excavation and pile head type. It was concluded that the excavation depth (He) with respect to pile length (Lp) has a significant effect on pile response. Among the three cases of He/Lp, the case of He/Lp=0.5 induced the maximum bending moment while the case of He/Lp= 1.5 induced the maximum pile lateral deflection. Moreover, the distance from the pile to the excavation site has also a significant influence on pile response and the induced bending moment in pile is inconsiderable after 9 m distance. Also, it is observed that the pile head type has an important effect on the pile behaviour especially in case of rigid head case.
- Published
- 2022
- Full Text
- View/download PDF
16. Frezeyle tornalamada takımda ortaya çıkan termal deformasyonların modellenmesi.
- Author
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Karagüzel, Umut, Bakkal, Mustafa, and Budak, Erhan
- Subjects
- *
CUTTING tools , *MILLING cutters , *GRINDING machines , *DEFORMATIONS (Mechanics) , *FINITE element method - Abstract
It is possible to increase the machined workpiece accuracy and productivity during turn-milling operation by modeling the cutting forces and thermally induced deformations on cutting tool. In order to achieve this task, the main objective of this study is to determine the thermally induced deformations on tool during turnmilling operation and reduce them by applying pressurized cooled air. In this study cutting forces, tool temperatures and deformations modelled by FEM coupled with analytical and mechanistic expressions are compared to those obtained by some series of experiments. It was shown in the study that those deformations could be upto 40% of the depth of cut during fine turn-milling. However they can be reduced by means of cooled air by 65%. Furthermore, tool wear and surface roughness values of machined workpiece were also measured and as it is stated in the paper that the surface values in fine turn-milling operation could be as good as they are in grinding operation. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
17. ÇİMENTO ESASLI MALZEMELERİN ÇEKME DAYANIMLARINI BULABİLMEK İÇİN YENİ BİR YÖNTEM ÖNERİSİ: ÜÇGEN PLAKA YÖNTEMİ.
- Author
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TÜRKER, Hakan T.
- Abstract
In this paper, a new test method to determine biaxial flexural tensile strength of cement based materials is proposed. A mortar triangular plate specimen is supported on three small spherical silver balls and loaded externally on a small spherical silver ball from the center of gravity of specimen. Yield line theory (YLT), which is a kinematic method of plastic analysis, is used to drive a simple equation for biaxial flexural tensile strength of cement based materials. In order to verify the derived equation, lots of triangular and prism mortar specimens were produced and tested according to the proposed model and three-point flexural test, respectively. Moreover, finite element analysis is also used to verify the derived equation and the results obtained from the experimental studies. It was concluded that FE analysis and experimental studies verified the proposed method and the derived closed-form equation for biaxial tensile strength of cement based materials. Experimental results also exhibited that biaxial tensile strength measured by proposed method is about 22% lower than that of the flexural strength obtained from three-point flexural test. [ABSTRACT FROM AUTHOR]
- Published
- 2015
18. YERALTI KABLOLARINDA SİLİNDİRİK EKRANLAMANIN PERFORMANS ANALİZİ.
- Author
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KÖROĞLU, Selim, UMURKAN, Nurettin, and KESLER, Selami
- Abstract
The shielding efficiency of cylindrical shields for three phase underground cable is investigated for several shields material using finite element method (FEM). This FEM model takes into account the nonlinear hysteretic behavior for ferromagnetic material in the shield. The shields are cylindrical shaped and the power cables are positioned in flat configuration. The shielding efficiency is compared for shields with the same geometry but several shielding materials with nonlinear hysteretic behavior (Magnetil and DX52, both from Arcelor-Mittal firm) and a non-ferromagnetic and electrically conducting shielding material (Aluminium). The paper investigates the influence of several parameters on shielding efficiency: the size of the shield radius, the current amplitude in the cable and the thickness of the shield. Magnetil shield material is the best in terms of shielding performance. The numerical models are validated with experimental results for without shield. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
19. Kallus Stabilizasyonu'nda Optimum Vida Konfigürasyonunun Belirlenmesi.
- Author
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ŞENSOY, Abdullah Tahir, KAYMAZ, İrfan, and ERTAŞ, Ümit
- Abstract
Distraction osteogenesis is a common clinical procedure to correct mandibular retrognathia cases. In spite of consolidated clinical use, lots of questions still remain to be answered concerning distraction osteogenesis. One of them is to determine the best screw configuration providing boneremodelling in a healthy way due to the stabilization of callus. In this study, some suggestions will be presented about the points "what best screw locations are" and "what the optimum screw quantity is". A three dimensional solid model was obtained by processing patient-specific computed tomography data in DICOM format. Teeth, cortical and trabecular bone segments were modelled separately with the segmentation process. Ramus and corpus segments were separated from each other by virtual surgery and corpus segment was positioned 11 mm forward. The distractors modelled were assembled into the mandible after modelling the callus. The volume meshes created for all the parts were transferred to a finite element software. Finite element analyses were run as bilaterally symmetric which means the same screw configurations were set for both sides of the mandible. The studies carried out in this paper have shown that screws located closer to the osteotomy line provide more stability, and triangular configuration has a better impact on stability than linear configuration. The reference stabilization case was identified as the scenario of using 22 screws in total, including 8 screws in ramus segment and 14 screws in corpus segment. This case was assumed as maximum stabilization case and other analyses were compared with this result. The results of the configuration including triangularly located 3 screws in ramus segment and closely located 2 screws near the osteotomy line in corpus segment have shown similarity with the reference stabilization case. The closest configuration to the reference case has been tried to determine by using as few screws as possible and has been recommended for clinical use. [ABSTRACT FROM AUTHOR]
- Published
- 2014
20. IE4 verim sınıfı senkron relüktans motor tasarımı
- Author
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Özçelik, Nezih Gökhan, Ergene, Lale, Elektrik Mühendisliği Ana Bilim Dalı, Elektrik Mühendisliği, and Electrical Engineering
- Subjects
Senkron Relüktans Motor ,Synchronous Reluctance Machıne ,Ie4 Effıcıency Level ,Ie4 Verim Sınıfı ,Sonlu Elemanlar Yöntemi ,Elektrik ve Elektronik Mühendisliği ,Fınıte Element Method ,Electrical and Electronics Engineering - Abstract
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2016, Thesis (M.Sc.) -- İstanbul Technical University, Instıtute of Science and Technology, 2016, Dünyada hızla artan enerji talebi karşısında enerji kaynaklarının sınırlı kalması 21. Yüzyılda enerji problemlemini beraberinde getirmiştir. Bu sorun son yıllarda mevcut kaynakların etkin kullanılmasına başka bir deyiş ile enerji verimliliği kavramının hayatımızda önemli bir yere konumlanmasına sebep olmuştur. Günümüzde neredeyse bütün endüstriyel ürünler enerji verim sınıflarına göre üretilip sınıflandırılmaktadır. Enerji kaynak yönetimini etkin şekilde planlayabilmek adına hükümetler tarafından hazırlanan regülasyonlar aracılığıyla enerji verimli ürünlere yönelik çalışmalar yoğun olarak sürdürülmektedir. Enerji tüketim verileri incelendiğinde, elektrik motorlarının tüketim olarak endüstriyel, konut ve ticari alanlarda en yüksek tüketim yapan araçlar arasında yer aldığı gözlemlenmiştir. Elektrik motorları özelinde ise en çok kullanılan motor türünün asenkron motorlar olduğu bilinmektedir. Yapılan bir araştırmaya göre asenkron motorların verim seviyelerinde yapılacak 1%’lik bir artış yıllık 20 milyar kWh değerinde bir enerji kazanamına yardımcı olacaktır [1]. Endüstriyel motorlar için halihazırda tariflenen en üst verim düzeyi IE3 olarak adlandırılmıştır. Buna karşın regulasyonlar aracılığı ile IE3 verim seviyesinden daha yüksek verim düzeyine sahip IE4 verim sınıfı motorlar yakın zamanda endüstride kullanılmaya başlanacaktır. Özellikle 7.5 kW ve altı güçlerde verim seviyelerinde iyileştirmeler yaparak IE3 verim seviyesindeki bir motoru maliyet ve üretilebilirlik kısıtları altında IE4 verim seviyesine taşımak 7.5 kW üstü güçlere kıyasla oldukça zordur Yapılan bu çalışmada, IE3 verim düzeyinde üç fazlı 2.2 kW gücünde dört kutuplu bir asenkron motorun yerine geçebilecek IE4 verim seviyesinde bir senkron relüktans motor tasarım çalışması gerçekleştirilmiştir. Senkron relüktans motorlar, asenkron motor ve kalıcı mıknatıslı senkron motorlar ile aynı stator yapısını kullanan, rotorunda yer alan bariyerler yardımı ile d ve q eksen takımlarında oluşan relüktans farkı prensibine dayalı olarak moment üretimi gerçekleştiren motorları temsil etmektedir. Senkron relüktans motorlar asenkron motorlar ile kıyaslandığında rotorunda herhangi bir iletken malzeme bulunmaması sebebiyle rotorunda bakır kayıplarının olmaması, kalıcı mıknatıslı senkron motorlar ile kıyaslandığında ise rotorunda sürekli mıknatısa ihtiyaç duymadan çalışabilmesi sebebiyle maliyet avantajını beraberinde getirmektedir. Bu çalışmada yukarıda tariflenen mevcut asenkron motorun stator yapısı kullanılarak rotor yapısı yeniden tasarlanarak senkron relüktans motor modelleri oluşturulmuştur. Tasarımlar oluşturulurken, senkron relüktans motor için en önemli tasarım girdilerinden olan bariyer sayısı, bariyer şekli, izolasyon oranı açısından tasarımlar irdelenerek en iyi çözüm bulunmaya çalışılmıştır. Çalışmada sayısal analiz yöntemlerinden biri olan sonlu elemanlar yöntemi kullanılmıştır. Sonlu elemanlar yöntemi kullanan paket bir program aracılığı ile iki boyutlu modelleme ve analiz yapılarak manyetik devre sonuçlarına ulaşılmıştır. Modelleme ve analiz basamaklarının doğru bir şekilde yapıldığından emin olmak için test sonuçları varolan mevcut asenkron motorun sonlu elemanlar yöntemi kullanan paket program ile modelleme ve analizi gerçekleştirilmiştir. Test ve manyetik analiz sonuçlarının tutarlı olduğu tespit edilerek mevcut asenkron motordan yola çıkılarak senkron relüktans motor tasarım çalışmaları yapılmıştır. iki boyutlu modelleme ve analiz yapılması sebebiyle uç sargı etkileri gibi bir takım parametreler ihmal edilerek tasarım çalışmaları gerçekleştirilmiştir. Buna karşın senkron relüktans motor tasarımlarının iki boyutlu olarak modelleme ve analize tabi tutulması sebebiyle tasarım çıktılarının elde edilmesi için geçen süre üç boyutlu modelleme ve analize kıyasla oldukça zaman tasarrufu sağlamıştır. Çalışmanın son basamağında belirlenen ve iyileştirilen bir tasarım modeli için prototip üretimi gerçekleştirilmiştir. Prototip motor performans testleri gerçekleştirilmiştir. Sonuç olarak belirlenen model için manyetik analiz sonuçları ve performans test sonuçlarının tutarlı olduğu ve IE4 verim seviyesini gerçeklediği gözlemlenmiştir., Increasing demand to energy in the 21st century brought the definition ‘energy problem’ as the resources are limited. More energy should be produced or less energy should be consumed with the same sources thus ‘energy efficiency’ entered into our lives. Today, all commercial products are strictly classified according to their energy efficiencies. In addition, these energy efficiency classes are strictly supervised with solid restrictions and regulations by governments and international organizations such as IEC or International Standards. When the energy demand is investigated, it is seen that electrical machines take a noticable percentage in it. Induction machines are the main motor type among commercial products. According to a recent research, a 1% increase in the induction machine efficiency would decrease the yearly demand by 20 billion kWh [1]. Currently, the highest commercial electrical machine efficiency class is identified as IE3 but with future regulations, this efficiency class would be IE4. Especially, for motor output powers under 7.5 kW, it is really hard to upgrade the efficiency class from IE3 to IE4. In this research paper, IE3 three phase 2.2 kW four pole induction machine is redesigned as synchronous reluctance motor (SynRM) with same output power but in IE4 energy efficiency class. SynRMs are type of electrical machines that uses the same stator structures with induction machines and permanent magnet motors. The difference is, when magnetic flux is generated, a difference between d and q axes are generated with help of specifically designed air barriers in rotor. Its basic working principle depends on the increased reluctance in q axis and minimum d axis reluctance. Its differences from switching reluctance motors are similar stator structures with other motor types and anisotropic distribution of saliency into rotor structure as air barriers. On the other hand both reluctance machines need a driver circuit. SynRMs can use a classical inverter motor driver circuit because of the general stator structure. Even SynRMs are as old as induction machines, the current developments in production and electronics technology made them a viable alternative to induction motors in late 20th and 21st century. When compared with induction machines, due to the lack of any conductive material in rotor, SynRMs have less copper losses and less temperature increases and also it is possible to design SynRMs more compact than induction machines because of its higher power/volume. And also it is possible to say that, due to the lack of any conductive material, rotor mass is lighter thus providing a less inertia and friction, ventilation losses. When compared with permanent magnet motors, it is cheaper because of the lack of magnets. SynRMs are temperature insensitive. The impact of high working temperatures effect less these motors than induction machines and permanent magnet because, high temperatures casuses increased resistance and negatively effects the permanent magnet properties. With these properties SynRMs, stands as a performance/price product between induction machines and permanent magnet motors. Today, SynRM is in the catalogues of many primary motor manufacturers and have a wide usage in industry. Currently, the widest usage is in variable speed systems such as pump and fan applications. Generally, the need of a driver circuit is a disadvantage for these motors but when variable speed applications and energy efficiency are considered, the usage of driver circuits is not a disadvantage. SynRM is also a hot topic in terms of scientific research. Since both cheaper and energy efficient motors are important, the development of this motor especially in terms of optimization is a frequent scientific topic. For example, by using ferrite magnets in air barriers, a hybrid permanent magnet SynRM is provided. With this hybrid structure it is possible to push energy efficiency limits to IE5 and IE6 classes. In this paper, the currently used commercial induction machine is redesigned as SynRM as stator structure and geometric dimensions are taken constants. While the designs are being formed, number of air barriers, air barrier geometry and isolation rate are taken as variables. Barrier numbers are investigated from one barrier to four barriers. As for shapes, angular, circular and circular-angular hybrid barrier shape are taken into account. By using these three variables, the best solution is searched. There are some variables that are not taken into account such as thickness of end rotor bridges and existence of barrier bridges. There are many researches made on SynRMs but first research made by Kostko, J.K. with a paper named “Polyphase Reaction Synchronous Motors”. In this paper, first theory of SynRMs are made and also first patent taken by Kostko himself in 1923 but as can be guessed in 1923, SynRM was not able to industrial induction machines due to lack of line start capabilities and relatively low efficiencies. Almost forty years later, a new work was made by Cruickshank, A.J.O., Menzies, R.W. and Anderson, A.F. in name of “Axially Laminated Anisotropic Rotors for Reluctance Motors introduced axially laminated SynRM. Axially laminated SynRM was more efficient than Kostko’s design and it could challenge the induction machines. Axially laminated SynRM was popular during 1960s and 1970s because of its capabilities but its manufacturing was a huge problem. Axially alignment of laminations needs a whole new production line so it wasnt industrially viable. Another work by Cruickshank, Menzies and Anderson put the mathematical theory of axially laminated SynRM. In this work, it still can be observed that axially laminated SynRM are a little behind the induction machines, they have higher saliency ratios than transverse laminated SynRM. In another work made by Honsinger, V.B. in name of “The Inductances Ld and Lq of Reluctance Machines” has put the general analytical model of SynRM in 1971. With this research it is possible to calculate the axes inductances analytically. Before this research, gaining high saliency ratios and torque values was arbitrary. In 1990s, SynRM has revived because of the latest developments in driver systems and production technologies. Papers written by Lipo, T.A. and Miller, T.J.E., has actually put that with driver systems SynRM is a viable alternative to induction machines especially in variable speed applications.Lipo’s researches were on the torque ripple optimization and Miller was working on driver design for SynRM. By the time, Vagati was also researching on saliency ratio improvements. Works made by Kamper, M.J., remarks the importance of finite element method to analyse and optimise SynRM. Another FEM work made by -, Magnussen and Sadarangani provides an understanding to optimization of barrier shape. Another interesting work is about a permanent magnet assisted SynRM which is designed for home appliance applications which shows that permanent magnet assisted SynRM can also be a viable alternative to permanent magnet machines. In paper, Finite Elements Method (FEM) is used as numerical method. FEM is a numerical method that allows us to investigate the problems. It is based on the discretization of a surface/product/material into finite elements and calculation of energies inside each discretized element. After calculation of energies, it is possible to calculate the potentials and fields. After calculation, it can be rebuilt to see the whole results.In contrary to its predecessor Finite Difference Method (FDM), FEM provides faster and more precise results than FDM. FDM, discretizes systems into equidistant grids, on the other hand, FEM discretizes systems into finite elements with dense elements for rapidly changing regions; sparse elements into slowly changing regions. By this method it is possible to obtain a flexibility. Today, FEM is the best computational method to analyze complex systems with help of powerful and comprehensive computer systems and programs. Thus results are taken with a program that allows both designing and analysing of an electrical machine. To ensure that the results are related, induction machine is designed and analysed with FEM program and the results are compared with available test results. After the confirmation of results are related, SynRM are designed and analysed. While analysing with FEM, end turns are omitted thus that two dimensional discretization can be made. Two dimensional analysis give faster results and less memory usage. At the last step of research, a prototype is produced based on the most efficient FEM model. According to the analyses models with four air barriers and angular barrier geometry have shown better performance than other models. As a result it is observed that, motor prototype test results and finite element analysis models are related and the production of a SynRM wtih IE4 energy efficiency class., Yüksek Lisans, M.Sc.
- Published
- 2016
21. Nokta direnç kaynağında ısıl ve yapısal analizlerin sonlu elemanlar yöntemi ile incelenmesi
- Author
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Yavuz, Başar, Vural, Murat, and Makine Mühendisliği Ana Bilim Dalı
- Subjects
Finite element method ,Mechanical Engineering ,Finite elements ,Finite element analysis ,Welding ,Makine Mühendisliği ,Welding methods ,Resistance welding - Abstract
Elektrik nokta direnç kaynağı endüstride sacların birleştirilmesi sırasında yaygın olarak kullanılan bir birleştirme yöntemidir. Özellikle sac parçaların yoğun olarak kullanıldığı beyaz eşya, otomotiv gibi endüstri kollarında kendine geniş kullanım alanı bulmaktadır. Bu yöntemde saclara yüksek basınç altında elekrik akımı uygulanır. Bu akım sonucu oluşan ısı enerjisi de kaynak çekirdeğinin oluşturulmasında kullanılır. Elektrik direnç nokta kaynğında elektriksel, ısıl, mekanik ve metalürjik olaylar birbirleriyle bağdaşık ve etkileşim halinde etki ederler. Bu durum sistemin tüm etkileri tek bir seferde gösterecek bir matematik modelin oluşturulmasını zorlaştırmaktadır. Bu nedenle genellikle analiz tek bir etki üzerine yapılır ve bu şekilde sonuca ulaşılmaya çalışılır. Elektrik akımı sonucu oluşan ısı Joule kanununa göre oluşur. Bu ısının bir kısmı ortam dağılırken çoğunluğu çekirdeğin ergimesi ve katılaşarak birleştirilmesi sırasında kullanılır. Yöntemde uygulanan baskı kuvveti de ayrıca önem arz etmektedir. Elektrot kuvvetlerinin uyguladığı kuvvet ergimiş haldeki kaynak çekirdeğine baskı oluşturur ve kaynak banyosunun dağılmasını engeller. Ayrıca kaynak bölgesi için zararlı olan atmosferik gazların ve toz parçacıklarının kaynak bölgesine ulaşmasını da engellemiş olur. Nokta direnç kaynağında akımın düzgün bir şekilde akması öenmlidir. Elektrotların uyguladığı baskı kuvveti bu akımın da doğru bir şekilde akmasına yardımcı olmaktadır.Bu parametrelerin doğru bir şekilde uygulanması ile kaliteli bir kaynak çekirdeği oluşumu sağlanır. Kaliteli bir kaynak birleştirmenin sahip olduğu dayanımı belirlemektedir. Bu nedenle kaynak kalitesi feragat edilebilecek bir özellik değildir. Sıcaklık dağılımı da metalürjik yapıyı dolayısıyla kaynak kalitesini ve dayanımı etkilemektedir. Bu çalışmada kaynak işlemi sonucunda ki ısı dağılımı, uygulanan baskı kuvvetleri nedeniyle oluşan deformasyon ve en yüksek gerilme durumlarının tespiti amacıyla sonlu elemanlar yöntemi kullanılarak bir model oluşturulmuştur. Daha sonra oluşturulan bu model yardımıyla bir sümülasyon çalışması yapılmıştır. Bu model yardımıyla deneysel olarak tespit edilmesi zor ve maliyetli olan nokta direnç kaynağına ait parametrelerin incelenmesi ekonomik ve hızlı bir şekilde sağlanmış olur.Ayrıca bu çalışma değişik malzemler için gerekli olan optimun ısıl ve kuvvet değerlerinin belirlenmesi sırasında veri kaynağı olarak kullanılabilir. Resistance spot welding is widely used in the industrial applications. It is used to join the sheet materials. RSW can be applied into the automation easily. Especially in automotive industry, it is the main welding method. It has thermal, structural and electrical phenomena together. This makes the experimental analysis very hard. In this method first we put sheet metals together, and then RSW electrodes applied pressure and give electrical current. After that, system stops the current flow while pressure is still applied. The last, system release the pressure and we can take the sheet metals. Current flow creates heat. Heat is created with Joule law. This heat melts the material. Sheet materials join and solidified in each other. In sheet metals heat should applied in small amount and in short time. Because, high heat flow in sheet metals create distortions. RSW has some parameters. Some parameters change the welding quality. Welding time and welding current have more effect than the other parameters. If we increase the welding time metals can burn. If we decrease the time then we take low quality weld area. Current is also important. According to Joule law current generates the heat. When the high current is applied, cracks can be created. When the low current is used, then we need more time for joining. This increases the weld area and decreases the welding quality. Heat affected zone is the most important topic in the all welding methods. This area has its own microstructure. Heating and cooling time determine the microstructure in this area. This area also identifies the quality of the welding. Because big heat affected zone changes the materials microstructure.In this paper, the thermal and structural analysis in resistance spot welding is examined with using finite element analysis. For this research S235, 304 and Al-7075 are used as sheet metal's material. Finite element analysis is widely used in engineering analysis. Engineers and researchers want to examine the system in order to make better systems. Generally, experimental analyses are expensive and hard to set up. With these difficulties, people make this analysis by using computers. Every machine or application can be modeled by using mathematical models. Some of them have many equations which are hard to solve. Computers are used to solve these equations. Finite element method is used for this approach. Every system has infinite points. Finite element method describes the system with finite points. Systems represented with these new model which gives the original system response. FEM gives the result with some errors. These all points are named as node. Nodes link with each other. These nodes create the elements. Elements can be 1, 2 or 3 dimensional. FEM is a numerical method. It is used in fluid mechanics, structural-thermal analysis, vibrations etc. FEM try to find changes in nodes by using some equations. In order to reach the solution, system should be fixed in some points.Finite element method has some steps in order to reach the results. First, system is divided into the small parts which are called as element. For the elements physical behaviors are defined. Equations are created for these elements. Unknown data are solved by using equation system. The last, desired element data are found.For the complex systems, thousands of equations are exist. When the system become more complex, then the equations are also become complex and hard to solve. These equations cannot solve analytically. Computers are used for this kind of situation. In some models computers cannot solve the system, as well.In this method, 1-D and 2-D elements are used. 1-D element carries the force parallel to its axes. These kinds of elements are used to model the bridge or truss system. The other option is using 2-D element. It is used generally pressure vessel system analysis. If the thickness of the material is much lower than the other dimensions, then 2-D elements are good for it. These elements are located differently in order to get 3-D system. On the other hand some computer programs use their own element types. Resistance spot welding is a very fast method and has different phenomena together. That's why researchers cannot easily test it experimentally. In order to examine the process, researchers use some FEM. However, researchers cannot analysis all phenomena in one step. In some cases, some special programs are used to examine. In thermal analysis, Fourier hear equation is used. Some reference points and initial conditions are added. After that thermal analysis can be done.In structural analysis, there are two basic equations. One of them is balance equations. The other one is structure equations. Von mises yield criterion is used for the structural system analysis.For this paper, two sheet metals are used. These metals are joint by using resistance spot welding. And also finite element model is used to examine the thermal and structural behavior while the welding operation has been done.Finite model has nearly 150000 nodes and 28000 elements. The model has 100x1x10 (mm) dimensions. Ambient temperature is added as 22 C. Three types of materials are used as sheet metals which are S235, 304 and Al-7075. All thermal and structural properties are added to the system. And 5000 N force applied to the system as an electrode pressure. In analysis process, we accepted that weld nugget has occurred in 0.3 s. After that system starts to cool while 5000 N force is applied in 1 s. As a result we try to understand thermal and structural behavior of system. Temperature distribution, deformation and max equivalent stress are found for three materials.For S235, we find the temperature distribution. Deformation is found 0.003 mm and max equivalent stress is measured as 1153 MPA.For 304, temperature distribution is found in different times. Deformation is found 0.003 mm and max equivalent stress is measured as 1147 MPa.For Al-7075, temperature distribution is found, as well. Deformation is measured as 0.03 mm and max equivalent stress is measured as 634 MPA during the welding operation.With this research, we get some outcomes. Temperature distribution has low heat flow until 1 second. After this, it cools in high rate.Temperature distribution has circular shape. It has not elliptical shape like the weld nugget.There are symmetrical deformation occurs around the weld nugget. This deformations occur due to electrode applied force.Max equivalent stress has max value instantly. However, this value decreases in some point after the welding operations.Max equivalent stress occurred around the weld nugget. And also some stress occurrence exists at the edge of the electrode applying area in the sheet metal.By using this research we can do some new research in the future. Optimum force can be found for different type of materials.The prediction of the deformation at the electrode can be examined.After the long using of electrode, some cracks may occur. We can predict the crack occurrence speed.Max equivalent stress should be decreased. We can use this research in order to decrease the max equivalent stress. 75
- Published
- 2015
22. Design and structural optimization of servo sheet metal folding machine
- Author
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Küçükduran, Rifat, Dilmeç, Murat, and NEÜ, Fen Bilimleri Enstitüsü, Makine Mühendisliği Anabilim Dalı
- Subjects
Büküm Makinesi ,Bending Machine ,Finite Element Method ,Folding Machine ,Caka Makinesi ,Sonlu Elemanlar Metodu ,Sac Büküm Makinesi ,Sheet Metal Bending Machine - Abstract
Yüksek Lisans Tezi, Sac metallerin kullanımı oldukça geniş alana yayılmıştır. Bu sebeple sac şekillendirme yöntemleri de gün geçtikçe gelişmektedir. Günümüze kadar ulaşan farklı sac şekillendirme yöntemleri bulunmaktadır. Sac bükmede yaygın olarak kullanılan manuel caka büküm makineleri büküm hassasiyetini yeteri kadar sağlayamamaktadır. Bu sebeple sac kalınlığının incelmesi ile ihtiyaç duyulan hassasiyet, caka büküm makineleriyle daha kolay yapılabilmektedir. Kompleks geometriye sahip sac ürünlerin üretimine olanak verecek caka büküm makineleri, operatörün de iş gücünü ve hata payını azaltacak niteliğe sahiptir. Servo elektrik motorlar ile birlikte bu makineler, seri üretimi yapılacak parçaların yarı otomatik olarak bükümüne de imkân verecektir. Bu tez çalışmasında geleneksel sac bükme makinelerinden caka makinesinin günümüz teknolojisine uygun olarak tasarlanması ele alınmıştır. Makine tasarımı SolidWorks yazılımı ile 3D olarak oluşturulmuştur. Büküm kuvveti, analitik ve sayısal hesaplamalar ile belirlenmiştir. Sayısal verileri elde etmek için SolidWorks Simulation sonlu elemanlar yazılımı kullanılmıştır., The use of sheet metals is widespread. Therefore, sheet metal forming methods are also developing day by day. There are different sheet forming methods that have survived to the present day. Manual sheet metal folding machines, which are widely used in sheet metal bending, do not provide sufficient bending precision. The required precision with the thinning of the sheet thickness can be achieved more easily with the folding bending machines. Folding machines, which will allow the production of sheet metal products with complex geometry, have the quality to reduce the labor force and margin of error of the operator. Together with servo electric motors, these machines will also allow semi-automatic bending of parts to be mass produced. In this paper, the design of the folding machine, one of the traditional sheet bending machines, in accordance with today's technology is discussed. The machine design was created in 3D with SolidWorks software. Bending force was determined by analytical and numerical calculations. SolidWorks Simulation finite element software was used to obtain the numerical data.
- Published
- 2022
23. DYNAMIC DISPLACEMENT AND STRESS ANALYSES OF CANTILEVER RETAINING WALLS CONSIDERING SOIL-STRUCTURE INTERACTION AND WALL FLEXIBILITY.
- Author
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ÇAKIR, Tufan and DAĞ, Serhat
- Abstract
Copyright of Sigma: Journal of Engineering & Natural Sciences / Mühendislik ve Fen Bilimleri Dergisi is the property of Sigma: Journal of Engineering & Natural Sciences / Mühendislik ve Fen Bilimleri Dergisi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2015
24. Parametric analysis of adjacent soil structures: Embankment-slope ınteraction
- Author
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Arama, Zülal Akbay, Akın, Muhammed Selahaddin, and Çinicioğlu, Safiye Feyza
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Finite element method ,Şev stabilitesi ,Numerical analyses ,Dolgu ,Slope stability ,Sonlu elemanlar yöntemi ,Güvenlik sayısı ,Factor of safety ,Sayısal analizler ,Embankment - Abstract
Uygulama sahalarındaki sınırlar sebebi ile yapıların şevler üzerine ve/veya içine inşa edilmesi durumunda yapıların davranışı şevlerin varlığından etkilenmekte olup bu durum etkileşimli davranış analizlerini gerektirmektedir. Yapı-şev sisteminin bütünsel stabilitesini etkileyen faktörler şevin yüksekliği ve eğimi, yapının şeve uzaklığı, temel zemini türü ve yapının geometrik durumudur. Bunların yanı sıra, dolguların yumuşak zeminler üzerine inşa edilmesi taşıma kapasitesi göçmesi ve şev stabilitesi gibi geoteknik problemleri de barındıran bir zemin-yapı etkileşimi problemi oluşturmaktadır. Bu çalışmanın amacı bütünsel davranış üzerinde farklılık oluşturan tüm faktörlerin davranış üzerindeki etki derecesinin belirlenmesidir. Bu amaçla, dolgu-şev ve temel zemininden oluşan etkileşimli sistemin davranışı birçok parametrik değerlendirme yapılarak iki boyutlu uzayda sonlu elemanlar analizleri yapılarak irdelenmiştir. It may be necessary to build structures on or adjacent to slopes due to the limited land areas. In such a case, behavior of the structures together with the adjacent slope is significantly affected by the presence of slopes. The variables influencing overall stability of the structure-slope system are the height and inclination of the slope, the distance of the structure to the crest of the slope, size of the structure and encountered types of foundation soils. Besides these, construction of embankments on soft soil is an important soil-structure interaction problem including many geotechnical challenges such as bearing capacity failure and global slope stability. The aim of this paper is to examine the degree of effectiveness of each of the influencing variables on the overall behavior. For this purpose, the behavioral aspects of the complete interactive system made up of embankment, slope and foundation soils, was analyzed by performing series of parametrical evaluations with finite element software in two dimensional media.
- Published
- 2018
25. H Tipi Hidrolik Pres Gövdesinin Yapısal Analizi ve Optimizasyonu
- Author
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Fatih Mehmet Mesut Elmas, Murat Dilmeç, and Osman Nuri Turhan
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Pressing ,H type hydraulic press,Finite element method ,Hydraulic press ,Materials science ,Mühendislik ,General Medicine ,Welding ,Finite element method ,law.invention ,H tipi hidrolik pres,Sonlu elemanlar yöntemi ,Engineering ,law ,Casting (metalworking) ,visual_art ,visual_art.visual_art_medium ,Composite material ,Sheet metal - Abstract
The presses used in forming the sheets have large sizes due to their large part sizes and the need for high pressing force and stroke. It is very difficult to use the casting method in the production of such press bodies. Therefore, each of the members constituting the press body is manufactured separately by combining sheet metal plates of a certain thickness with the welding. However, in most cases the thickness of the plates forming the body is used experimentally and excessively. In this paper, thickness optimization of the H type press machine capacity of 300 tons has been realized. In this study, thickness optimization of H type hydraulic press frame has been conducted by using finite element analysis. So, thicknesses of the plate create press frame has been decreased and material saving has been ensured., Sac metal şekillendirme proseslerinde kullanılan presler, işlenecek parça boyutlarının büyük olması, büyük presleme kuvveti ve strok ihtiyacından dolayı büyük ebatlara sahip olmaktadırlar. Sac metal işleme preslerinin gövde imalatında döküm yöntemini kullanmak zordur. Bu nedenle belirli kalınlıkta sac plakalar kaynak yöntemi ile birleştirilerek pres gövdesi oluşturulmaktadır. Ancak çoğu zaman gövdeyi oluşturan plakaların kalınlıkları tecrübi olarak ve gereğinden fazla kullanılmaktadır. Bu çalışmada, sonlu elemanlar analizi kullanılarak 300 ton kapasiteli H tipi pres gövdesinin nümerik kalınlık optimizasyonu yapılmıştır. Böylece pres gövdesini oluşturan plakaların kalınlıkları azaltılmış ve malzeme tasarrufu sağlanmıştır
- Published
- 2018
26. Kendinden takviyeli polipropilen esaslı termoplastik kompozit levhalarda delik etkisinin deneysel ve sayısal olarak incelenmesi
- Author
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Kurtuluş, Orhan, Yazıcı, Murat, Uludağ Üniversitesi/Fen Bilimleri Enstitüsü/Otomotiv Mühendisliği Anabilim Dalı., and Otomotiv Mühendisliği Ana Bilim Dalı
- Subjects
Finite element method ,Delik etkisi ,Open-hole effect ,Mekanik özellikler ,Sonlu elemanlar yöntemi ,Engineering Sciences ,Mechanical properties ,Kendinden takviyeli termoplastik kompozit malzemeler ,Self reinforced thermoplastic composite materials ,Mühendislik Bilimleri - Abstract
Otomotiv endüstrisi için ağırlık azaltma çalışmalarına yönelik yapılan araştırmalar son yıllarda kompozit malzemeleri ön plana çıkarmıştır. CO2 salınımına getirilen yasal sınırlamalar nedeniyle özellikle otomotiv endüstrisinde özgül mukavemet, şekil verilebilirlik, hafiflik ve geri dönüşüm yetenekleri ile ağırlık azaltmak ve gerekli mekanik özellikleri karşılamak amacıyla termoplastik matrisli kompozitler kullanılmaya başlamıştır. Kendinden takviyeli termoplastik kompozitler ise %100 geri dönüşüm yeteneği ve darbe dayanımlarının yüksek olması nedeniyle, kompozit malzemelerin özel bir alanını oluşturmaktadır. Bu tez çalışmasında, laminasyon yöntemiyle üretilmiş kendinden takviyeli polipropilen esaslı termoplastik kompozit plakaların çekme ve kayma deneyleri yapılmıştır. Daha sonra delik etkisini incelemek için, kompozit plakalara ASTM standardına göre delik açılmış ve çekme deneyleri tekrarlanmıştır. Deney sonuçlarını incelemek ve kıyaslamak için Abaqus yazılımında kompozit plakaların analizleri yapılmıştır. Researches on weight reduction for the automotive industry have been focused on composite materials in recent years. Due to the legal restrictions on CO2 emissions, thermoplastic matrix composites are now being used especially in the automotive industry to reduce weight with specific strength, formability, lightness and recycling capabilities and to meet the required mechanical features. Self-reinforced thermoplastic composites constitute a special area of composite materials thanks to their 100% recyclability and high resistance against impact.conditions.In this thesis paper, tensile and shear tests were conducted for self-reinforced polypropylene based thermoplastic composite plates produced by lamination method. Then, the composite plates were drilled according to the ASTM standard in order to determine the open hole-effect and the tensile tests were repeated. Composite plates were analyzed in Abaqus software in order to examine and compare the results of the experiments. Rollmech Automotive Anonim Şirketi Maysan Mando Otomotiv Parçaları Sanayi ve Ticaret Anonim Şirketi
- Published
- 2017
27. Yeni bir çatlaklı çubuk eleman ile eğri eksenli çubuklarda çatlağın konumunun ve derinliğinin tespiti
- Author
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İpek, Can Altuğ, Tüfekci, Ekrem, and Makine Mühendisliği Ana Bilim Dalı
- Subjects
Finite element method ,Mechanical Engineering ,Fracture mechanics ,Curved beams ,Makine Mühendisliği ,Genetic algorithms ,Fault detection - Abstract
Çubuklar, diğer yapı elemanlarına göre, basitliklerinin getirdiği kullanım yaygınlığı sebebiyle mühendislik alanında oldukça önemli bir yere sahiptir. Geniş kullanım alanları sebebiyle çubuklar, yıllar boyunca araştırmacılar arasında önemli ve popüler bir konu olmuş ve olmaya da devam etmektedir. Çubuklar düz veya eğri gibi farklı formlara sahip olabilmekle birlikte, bu tez çalışmasında ele alınan eğri eksenli çubuklardır.Bu çalışmada, ekseni üzerindeki herhangi bir konumda ve derinlikte çatlağa sahip olan sabit eğrilikli ve sabit kesitli eğri eksenli çubuklar için, yeni bir çatlaklı çubuk sonlu eleman formülasyonu geliştirilmiş ve kesin çözümden uyarlanmış sonlu eleman yöntemi uygulanmıştır. Ardından bu yeni geliştirilmiş çatlaklı çubuk eleman ile kurgulanmış sonlu eleman yöntemi, ters problem için kullanılmış ve doğal frekans değerleri bilinen çatlaklı bir çubuk için, çatlağın eksen üzerindeki konumu ve derinliği tespit edilmiştir. Ters problemin çözümünde bir optimizasyon yöntemi olan genetik algoritma kullanılmıştırBirinci bölümde, çubuk teorisi hakkında kısaca bilgi verilmiş, çalışmanın amacı ve kapsamı belirtilmiştir. Çubuk üzerindeki çatlağa yönelik yapılan çalışmalar incelenmiş. Ardından çubuk üzerindeki çatlağın tespiti için kullanılan ters problemin çözümü için, literatürde kullanılan yöntemler hakkında bilgi verilmiştir.İkinci bölümde, değişken eğrilikli ve değişken kesitli eğri eksenli çubukların düzlem içi genel denklemleri verilmiştir. Ardından çember eksenli ve sabit kesitli eğri eksenli çubuklar için düzlem içi statik denklemlerin başlangıç değerleri problemi yoluyla çözümü verilmiştir. Asal matrisin terimleri elde edilmiştir.Üçüncü bölümde, bir önceki bölümde elde edilen eğri eksenli çubukların statik denkleminin analitik çözümü kullanılarak, sonlu eleman formülasyonu uyarlanmıştır. Çember eksenli ve sabit kesitli, üzerinde çatlak ve benzeri herhangi bir hata bulunmayan bir çubuk elemanının rijitlik ve kütle matrisleri elde edilmiştir.Dördüncü bölümde, kırılma mekaniği hakkında kısaca bilgi verilmiş, çatlağın çubuk üzerindeki etkisinden bahsedilmiş ve çatlağın yarattığı yerel esneklik matrisi elde edilmiştir. Ardından çubuk ekseni üzerindeki herhangi bir konumda ve derinlikteki çatlağa sahip bir çubuk için, yeni bir çatlaklı çubuk eleman geliştirilmiştir. Bu yeni çatlaklı çubuk eleman için rijitlik matrisi elde edilmiştir.Beşinci bölümde, daha önceki bölümlerde elde edilen çatlaksız ve çatlaklı çubuk elemanların rijitlik ve kütle matrisleri kullanılarak modellenmiş çember eksenli ve sabit kesitli eğri eksenli çubukların özdeğer problemleri çözdürülmüş ve hem çatlaksız hem de çatlaklı eğri eksenli çubuklar için doğal frekans değerleri elde edilmiştir. Elde edilen doğal frekanslar, hem literatürdeki çalışmalar ile karşılaştırılmış; hem de İstanbul Teknik Üniversitesi Makina Fakültesi'ndeki Mukavemet Birimi Laboratuvarı'nda yapılan deneylerden elde edilen sonuçlar ile karşılaştırılmıştır.Altıncı bölümde, ters problem hakkında kısaca bilgi verilmiş, bir optimizasyon yöntemi olan genetik algoritma (GA) tanıtılmıştır. Ardından bir önceki bölümde verilen çatlaksız ve çatlaklı çubukların doğal frekansları kullanılarak, GA yardımıyla çatlağın eksen üzerindeki konumu ve derinliği tespit edilmiştir. Yedinci bölümde, çalışmanın kapsamı kısaca ele alınmış, elde edilen sonuçlar yorumlanmış ve yeni önerilerde bulunulmuştur. Beams, comparing with any other structural elements, have a very important role in engineering field considering their common usage due to their simplicity. This makes them a very hot topic for researchers from past to present throughout the centuries. Beams have a variety of forms according to their geometry such as straight, curved, tapered. However, only the curved beams are considered in this study.A structure has a design aim to fulfil during service. Beams are the main elements to build the structure and every one of them is very important for that structure to meet the design criteria. However, a notch or crack in the beam, dramatically reduces the life span of the beam and this might create a catastrophic failure if it's not detected on time. There are some methods to detect the crack in the beam, however they can be very expensive or very time consuming. This study aims to create a faster, easier way to detect the crack by using finite element method.In this study, a finite element formulation is derived from analytically solved static problem considering a cracked beam with constant curvature and constant cross-section. Since the basis of the formulation derived from the exact solution, it has no simplification. This means that, shear deformation, axial deformation and rotatory inertia is not neglected. Then, a new curved cracked beam element is introduced. This new cracked curved beam element contains a crack on an arbitrary location and arbitrary depth which can be defined by the user. Using this new cracked curved beam element's and also the intact beam element's stiffness and mass matrices, intact and cracked curved beams are modelled with the finite element formulation which is derived from exact solution. Those modelled intact and cracked curved beams are then used to solve the inverse problem in order to find the crack parameters such as location and depth. During the inverse problem, genetic algorithm (GA) is implemented as an optimization method. Main aim of this study is to detect the crack's location and depth with using a new cracked curved beam element. A crack on the beam creates a local flexibility. In the light of this phenomena, a local flexibility matrix is constructed and transfer matrices are used to define this local flexibility on the intact curved beam element. By doing so, a new cracked curved beam element that contains a crack is then ready to be used to formulate the finite element method. Since this new cracked curved beam element contains an inherent crack, it can be used to model any number of crack in the beam. In this study, only one crack is considered since the main focus is to prove that the new cracked curved beam element is sufficient enough to model the curved cracked beam.In the first chapter, a general view for curved beams, where they are used and their importance is presented. After that, the presence of the crack and its effect on the beam is given. A detailed review for the studies in the literature about cracks in the beam is stated. These studies contain the effect of the crack to the beam considering vibration properties such as natural frequency and mod shapes. It is stated that the crack induces a local flexibility and diminishes the natural frequencies of the beam. It is seen from these studies that, there are many ways to model the crack, but generally the crack is modeled as link or spring. After generic information about the crack, the studies in the literature about inverse problem is given. It is declared that, the inverse problem needs to be solved in order to detect the cracks in the beam. Main idea of the inverse problem is the find the crack parameters such as location and depth of the crack. The inverse problem is approached from many different ways by researchers. Conventional hard computing methods are very time consuming considering an inverse problem. It is observed that the overall consensus if to use an optimization method to solve the inverse problem. That's why, it is mainly solved by the optimization methods such as genetic algorithm, neural networks, fuzzy logic. Papers which uses those different optimization methods for the inverse problem to detect the crack are documented. In this study, an optimization method called genetic algorithm is used in order to perform inverse problem.In the second chapter, in-plane governing equations of a curved beam are presented for the static problem. After that, initial value boundary problem is used to solve those in-plane equations. The resultant equations are given. These exact solutions are valid for any curved beam, including those curved beams which have variable curvature and variable cross-section. The solution also does not depend on the loading and boundary condition. Then, considering a curved beam with a circular curvature and constant cross section, analytical expressions of the fundamental matrix is derived.In the third chapter, finite element method is derived from the exact solution. Two-node six degree of freedom beam element is presented for the flawless curved beam. Using the fundamental matrix which was obtained in the previous chapter, the stiffness matrix for the intact beam element is constructed. Also the generic kinetic energy expression is used to obtain the mass matrix of the beam element. Considering those matrices, the classic finite element assembly is sufficient to model the flawless curved beam.In the fourth chapter, a brief review about the fracture mechanics is given. Stress intensity factors and the fracture modes are presented. Using the energy method approach, the local flexibility induced by the crack is found. A local flexibility matrix is constructed. With the help of the transfer matrices, a new cracked curved beam element which has a crack on an arbitrary location and depth is obtained. Using this new beam element, a curved beam with a crack can be easily modelled.In the fifth chapter, previously found stiffness and mass matrices of intact and cracked beam element are used to assemble the beam and then eigenvalue problem is solved to obtain the natural frequencies. It needs to be stated that the mass matrix for the intact and the cracked beam is the same. After that, studies in the literature which calculates the natural frequencies analytically and experimentally are presented. A comparison is made between the results of this study and the studies in the literature. It is stated that the results of the studies in the literature and this thesis study are well met.In the sixth chapter, the importance of the detection of the crack is given. The inverse problem is defined. It is stated that the any hard computing method is inadequate when the problem is very complex and hard to solve. It would require a lot of time to solve those problems with hard computing methods. It is described that, the inverse problem in this thesis study is the detecting the crack's location and depth on a curved beam with a circular curvature and constant cross-section. In order to detect the crack, previously found natural frequencies are used. Those frequencies are the product of a beam that is modeled with the new cracked beam element. Methods to solve the inverse problem is then defined. Although there are many ways to solve the inverse problem, an optimization method which is called genetic algorithm is chosen. General review of the genetic algorithm is presented. The cost function of the optimization problem is given. Relative error is used as the cost function. The difference between intact and cracked beam regarding experimentally determined natural frequencies is presented. After that, the difference between intact and cracked beam, which are constructed with the method of finite element, considering natural frequencies is found. These two sets of differences are then used on the cost function. By doing so, it is wanted to diminish the errors of the experiment. Also the weighting factor is determined. This factor is used to reduce the effect of the measurement noise. Moreover, using the natural frequencies of an intact and the cracked beams as an input, inverse problem is solved to detect the crack's location and depth. At first, arbitrary chosen crack parameters are tried to be found. Secondly, the natural frequencies, which is presented in the study in the literature, is used to see the efficiency of the new cracked beam element. Thirdly, an experiment in the laboratory of Istanbul Technical University is made and the natural frequencies from that experiment is used to solve the inverse problem to find the crack's location and depth. It is stated that the finite element formulation with a new cracked beam element which is presented in this thesis study is giving coherent results with an acceptable absolute error.In the seventh chapter, the scope of the study is given with results and discussions. Also some suggestions are made for the further studies. 75
- Published
- 2017
28. Yüksek sıcaklık ve basınç altında çalışan bir santrifüj pompanın şasi ve gövde gerilme analizi
- Author
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Cebeci, Okan, Kurt, Mustafa, Makine Mühendisliği Anabilim Dalı, and Makine Mühendisliği
- Subjects
Finite element method ,Sonlu elemanlar metodu ,Gerilme analizi ,Mesh yapıları ,Stress analysis ,Mechanical Engineering ,Statik analiz ,Makine Mühendisliği ,Static analysis ,Machine engineering ,Centrifugal pumps ,Santrifüj pompalar ,Makina mühendisliliği ,Mesh structures - Abstract
ÖZETYÜKSEK SICAKLIK VE BASINÇ ALTINDA ÇALIŞAN BİR SANTRİFÜJ POMPANIN ŞASİ VE GÖVDE GERİLME ANALİZİDünya nüfusunun artması, teknolojik gelişmeler ve globalleşen dünya üretimlerde rekabet ortamını giderek arttırmaktadır. Bunların yanı sıra piyasadan gelen taleplere hızlı cevap verilmesi, kalite ve sürekliliğin yerine getirilmesi gerekmektedir. Özellikle ilaç, enerji, petro-kimya ve kağıt endüstrisi gibi hayatı birçok alanda etkileyen sektörlerde, yüksek güvenilirlik ve hassasiyet gerektiren sistemlerin taleplerinin giderilmesi büyük önem taşımaktadır. Pompa ve pompa sistemleri, üretim süreç taleplerinin karşılanması açısından proseslerin kalbi olarak sayılabilmektedir. Bu yüzden 7/24 çalışmakta olan bu proseslerde, pompalardan öncelikli beklenti yüksek güvenilirlik ve süreklilik olmuştur.Son yıllarda gelişen bilgisayar teknolojisi ile birlikte, pompa tasarım aşamalarında yapısal ve akış analizlerinin sayısal olarak incelenmesine imkan vermiş, tasarımların iyileştirilmesi ve optimize edilmesi sanal ortamında yapılarak kalıp, model ve deneysel maliyetlerin en aza indirgenmesine ve zaman kayıplarının azaltılmasına olanak sağlanmıştır.Bu çalışmada API 610 standart’ına göre tasarımı yapılmış bir uçtan emişli konsol tip pompada meydana gelen gerilme, deformasyon, et kalınlığının uygunluğu ve mil deformasyonun uygunluğunun tespiti amacıyla, bilgisayar ortamında sonlu elemanlar yöntemi kullanılarak analizler yapılmıştır. Sayısal analizler ANSYS Workbench ticari yazılımı altında gerçekleştirilmiştir. Birinci statik analiz durumunda pompa gövdesine uygulanan maksimum basınç altında hesaplanan et kalınlığının kontrolü yapılmıştır. Gövde üzerinde meydana gelen gerilme ve deformasyon değerleri ölçülerek, hesaplanan gövde et kalınlığı optimize edilmiştir. İkinci statik analiz durumu, pompa emme ve basma flanşlarında meydana gelen flanş yüklerinin etkisinden kaynaklı, pompa mili ve salmastra yatağında meydana gelen deformasyon ve gövde üzerinde meydana gelen gerilme değerleri incelenmiştir. Deformasyon değerlerinin azaltılmasına ilişkin, mil deformasyonunu doğrudan etkileyen pompa şasinin farklı modelleri tasarlanmıştır.--------------------ABSTRACTBASEPLATE AND BODY STRESS ANALYSIS OF A CENTRIFUGAL PUMP WORKING UNDER HIGH TEMPERATURE AND PRESSUREIncreasing world population, developing technology and globalization lead to a harder competition in industrial environments. Furthermore, fast response to customer demands, ensuring high quality and its sustainability is given priority. Especially in sectors affecting daily life like pharmaceutical, chemical, energy, petrochemical, pulp and paper industries it is crucial to meet the demands of systems which require high reliability and sensitivity. Pumps and pumping systems can be named as the heart of production processes. Therefore, in this kind of processes running 7/24, prior expectation from pumping units is high reliability and sustainability.Recent advancements in computer technology enabled to conduct numeric calculations for static and CFD analysis in pump design. It is made possible to make the design optimization in digital platform thus reducing molding, prototype production and experimental validation costs and accordingly save considerable amount of time.In this study, static analysis is conducted for a API 610 overhung pump using finite element method in ANSYS Workbench platform. It is aimed to calculate the stress and deformation field and to check whether allowable shaft deformation criteria is achieved. In the first step specified volute thickness is checked under maximum allowable working pressure. Stress and deformation field are controlled at various sections and thickness is optimized step by step accordingly. In the second step, pump shaft deflection, stuffing box deflection and stress values at volute are analyzed under suction and discharge flange loads. Different baseplate configurations are designed which has direct influence on the shaft deflection values.
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- 2017
29. A performance comparison of conventional and transverse flux linear switched reluctance motors
- Author
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Krishnan Ramu and Nurettin Ustkoyuncu
- Subjects
Engineering ,General Computer Science ,Magnetic reluctance ,business.industry ,Flux ,Manufacturing cost ,Finite element method ,Switched reluctance motor ,Reluctance motor ,Magnetomotive force ,Control theory ,Path (graph theory) ,Linear switched reluctance motor,transverse flux motor,force density ,Electrical and Electronic Engineering ,business - Abstract
This paper presents a comprehensive comparison between conventional (longitudinal flux) linear switched reluctance machines (CLSRMs) and transverse flux linear switched reluctance machines (TLSRMs) so as to enable engineers to choose a structure suitable for their applications. A commonly-used single-sided CLSRM and 4 different TLSRM structures are considered for the comparison. For a fair comparison of the 2 types of LSRMs, equal dimensions, including equal length and magnetomotive force, are applied as much as possible. The analytical approach and 3-dimensional finite element analysis (FEA) are employed to obtain the performance of these machines. It is proven analytically that the CLSRM has a higher force capability compared to TLSRMs by as much as 6 times under linear B-H characteristic operating points. The results are reinforced by the FEA-based performance results. Furthermore, the CLSRMs are simpler to construct, resulting in lower manufacturing cost and thus paving an easier path for their market acceptance than TLSRMs. These results make CLSRMs the structure of choice for linear-switched reluctance motors.
- Published
- 2015
30. Kauçuk Burçların Hiperelastik Modellenmesi ve Sonlu Elemanlar Yöntemi ile Analizi
- Author
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Merve Yavuz Erkek, Caner Güven, and Necmettin Kaya
- Subjects
bushing ,Computer Science::Robotics ,Bushing,rubber,finite element method,hyperelastic model ,lcsh:T ,lcsh:TA1-2040 ,Quantitative Biology::Tissues and Organs ,finite element method ,rubber ,hyperelastic model ,lcsh:Engineering (General). Civil engineering (General) ,lcsh:Technology ,Kauçuk burç ,optimizasyon ,sonlu elemanlar analizi ,hiperelastik malzemeler - Abstract
The objective of this paper is to obtain stiffness curves of rubber bushings which are used in automotive industry with hyperelastic finite element model. Hyperelastic material models were obtained with different material tests. Stress and strain values and static stiffness curves were determined. It is shown that, static stiffness curves are nonlinear. The level of stiffness affects the vehicle dynamics behaviour., Bu çalışmada, otomotiv endüstrisinde kullanılan kauçuk burçların hiperelastik modellenmesi yapılmış ve sonlu elemanlar yöntemi ile statik analizleri gerçekleştirilerek rijitlik eğrileri çıkarılmıştır. Kauçuk malzemelerin hiperelastik malzeme modelleri malzeme testleri sonucu belirlenmiştir. Kauçuk burcun belli oranda x,y,z eksenleri yönünde sıkıştırılması ve eksenel yönde burulması sonucu oluşan gerilmeler ve yer değişimleri incelenerek statik rijitlik eğrileri çıkarılmıştır. Rijitlik eğrilerinin doğrusal olmayan karakteristikte olduğu belirlenmiştir. Burç rijitlik değerleri araçlarda sürüş dinamiğini etkileyen önemli parametrelerden birisidir.
- Published
- 2015
31. Sensitivity analysis and optimum design for the stator of synchronous reluctance machines using the coupled finite element and Taguchi methods
- Author
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Hossein Azizi and Abolfazal Vahedi
- Subjects
Engineering ,General Computer Science ,Parametric analysis ,business.industry ,Magnetic reluctance ,Stator ,Taguchi design ,Finite element method ,Synchronous reluctance machines,Taguchi method,finite element method,orthogonal array,sensitivity analysis ,law.invention ,Taguchi methods ,Control theory ,law ,Sensitivity (control systems) ,Electrical and Electronic Engineering ,Orthogonal array ,business - Abstract
This paper presents an investigation of the effect and optimization of stator geometry design parameters on the performance of synchronous reluctance machines (SynRMs). The level of importance of the stator design variable on the characteristic of the SynRM is determined using both the Taguchi method and a parametric analysis. An optimum design parameter combination is obtained using sensitivity analysis along with signal-to-noise ratio results. The 2-dimensional finite element model (FEM) of a SynRM is used to perform a sensitivity analysis and construct a Taguchi design of the experiment. The FEM simulation results confirm that the performance of the SynRM can be improved significantly in comparison with the initial design, using the proposed Taguchi method.
- Published
- 2015
32. Hyperelastic modelling and finite element analysing of rubber bushing
- Author
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Güven, Caner, Uludağ Üniversitesi/Teknik Bilimler Meslek Yüksek Okulu/Kalıpçılık Programı., Uludağ Üniversitesi/Mühendislik Fakültesi/Makine Mühendisliği Bölümü., and Erkek, Merve Yavuz
- Subjects
Kauçuk burç ,Optimizasyon ,Sonlu elemanlar analizi ,Finite element method ,Bushing ,Rubber ,Hyperelastic model ,Hiperelastik malzemeler - Abstract
Bu çalışmada, otomotiv endüstrisinde kullanılan kauçuk burçların hiperelastik modellenmesi yapılmış ve sonlu elemanlar yöntemi ile statik analizleri gerçekleştirilerek rijitlik eğrileri çıkarılmıştır. Kauçuk malzemelerin hiperelastik malzeme modelleri malzeme testleri sonucu belirlenmiştir. Kauçuk burcun belli oranda x,y,z eksenleri yönünde sıkıştırılması ve eksenel yönde burulması sonucu oluşan gerilmeler ve yer değişimleri incelenerek statik rijitlik eğrileri çıkarılmıştır. Rijitlik eğrilerinin doğrusal olmayan karakteristikte olduğu belirlenmiştir. Burç rijitlik değerleri araçlarda sürüş dinamiğini etkileyen önemli parametrelerden birisidir. The objective of this paper is to obtain stiffness curves of rubber bushings which are used in automotive industry with hyperelastic finite element model. Hyperelastic material models were obtained with different material tests. Stress and strain values and static stiffness curves were determined. It is shown that, static stiffness curves are nonlinear. The level of stiffness affects the vehicle dynamics behaviour.
- Published
- 2015
33. Betonarme Perde Duvarların Sonlu Eleman Analizinde Aderans Kaymasının Uygulanması
- Author
-
İlker Kazaz
- Subjects
Materials science ,Anderans kayması,betonarme perde,sonlu eleman yöntemi,ANSYS ,Shear wall ,Bond slip ,Bond-Slip,Reinforced concrete shear wall,finite element method,ANSYS ,Composite material ,Reinforced concrete ,Finite element method - Abstract
Transfer of tensile forces from reinforcing steel into the surrounding concrete affects the behavior of reinforced concrete members. This transfer relies on the bond action between the steel and the concrete. Under monotonic loading the part of bond strength due to chemical adhesion is easily exhausted and bearing against the lugs is the primary load-transfer mechanism at loads near the ultimate. These stresses cause internal cracking of concrete at the steel-concrete interface. This paper deals with the finite element modeling of the bond-slip and its application due to internal cracking of the first layer of concrete surrounding the bar and the bending and/ or cracking of the small concrete teeth near the bar lugs. A previously proposed constitutive steel stress-bond slip relation by Mirza and Houde (1979) was used in finite element analysis of reinforced concrete shear wall specimens and the results were presented., Donatı ve onu çevreleyen beton arasında gerçekleşen yük geçişleri betonarme elemanların davranışını önemli ölçüde etkiler. Bu gerilme geçişleri beton ve çelik arasındaki kenetlenmeye (aderansa) bağlıdır. Düzgün artan yükler altında aderansın kimyasal yapışma sonucu oluşan kısmı kolayca devre dışı kalır ve yük aktarımı nervür dişleri etrafında oluşan karmaşık bir gerilme durumunun bileşkesi olarak ortaya çıkan kayma gerilmeleri tarafından sağlanır. Nervür etrafında oluşan bu gerilme yoğunlaşması nervür dişleri etrafındaki betonda içsel çatlamaların meydana gelmesine neden olur. Bu çalışma, donatıyı saran betonda içsel çatlamalar sonucu beton-çelik ara yüzeyinde oluşan aderans kaymasının sonlu elemanlarla modellenmesini içermektedir. Donatı çeliği gerilmesi-bağ kayması arasındaki ilişki için Mirza ve Houde (1979) tarafından önerilen bir bağıntı sonlu eleman uygulamalarında kullanılmıştır ve sonuçlar özetlenmiştir.
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- 2015
34. A new test method for biaxial tensile strength of cement based materials: Triangular plate method [Çimento esasli malzemelerin çekme dayanimlarini bulabilmek için yeni bir yöntem önerisi: Uçgen plaka yöntemi]
- Author
-
Türker H.T. and İskenderun Teknik Üniversitesi
- Subjects
Condensed Matter::Materials Science ,Finite element method ,Cement based materials ,Biaxial tensile strength ,Triangular plate method ,Physics::Classical Physics ,Yield line method - Abstract
In this paper, a new test method to determine biaxial flexural tensile strength of cement based materials is proposed. A mortar triangular plate specimen is supported on three small spherical silver balls and loaded externally on a small spherical silver ball from the center of gravity of specimen. Yield line theory (YLT), which is a kinematic method of plastic analysis, is used to drive a simple equation for biaxial flexural tensile strength of cement based materials. In order to verify the derived equation, lots of triangular and prism mortar specimens were produced and tested according to the proposed model and three-point flexural test, respectively. Moreover, finite element analysis is also used to verify the derived equation and the results obtained from the experimental studies. It was concluded that FE analysis and experimental studies verified the proposed method and the derived closed-form equation for biaxial tensile strength of cement based materials. Experimental results also exhibited that biaxial tensile strength measured by proposed method is about 22% lower than that of the flexural strength obtained from three-point flexural test.
- Published
- 2015
35. A NEW TEST METHOD FOR BIAXIAL TENSILE STRENGTH OF CEMENT BASED MATERIALS: TRIANGULAR PLATE METHOD
- Author
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Turker, Hakan T. and İskenderun Teknik Üniversitesi
- Subjects
finite element method ,biaxial tensile strength ,cement based materials ,yield line method ,Triangular plate method - Abstract
WOS: 000368517800015, In this paper, a new test method to determine biaxial flexural tensile strength of cement based materials is proposed. A mortar triangular plate specimen is supported on three small spherical silver balls and loaded externally on a small spherical silver ball from the center of gravity of specimen. Yield line theory (YLT), which is a kinematic method of plastic analysis, is used to drive a simple equation for biaxial flexural tensile strength of cement based materials. In order to verify the derived equation, lots of triangular and prism mortar specimens were produced and tested according to the proposed model and three-point flexural test, respectively. Moreover, finite element analysis is also used to verify the derived equation and the results obtained from the experimental studies. It was concluded that FE analysis and experimental studies verified the proposed method and the derived closed-form equation for biaxial tensile strength of cement based materials. Experimental results also exhibited that biaxial tensile strength measured by proposed method is about 22% lower than that of the flexural strength obtained from three-point flexural test.
- Published
- 2015
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