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Öğe ANALYSES OF LAMINATED CANTILEVER COMPOSITE BEAMS BY MODEL ORDER REDUCTION TECHNIQUES(TAYLOR & FRANCIS INC, 2011) Cunedioglu, YusufIn this study, a laminated cantilever composite beam is studied in frequency domain by using some popular model order reduction techniques. In the analyses, component mode synthesis (CMS) and quasi-static mode synthesis (QSM1, QSM2) methods are applied to semi-discrete finite element equations to obtain reduced order models for structural analyses. The performance of the model order reduction methods is compared. In addition, fiber orientation, stacking sequence, ply thickness, and its location effects on the number of modes of the methods and on the natural frequencies are investigated. Results reveal that the performance of the QSM2 method is found to be better than the others. It is observed that the fiber orientation, stacking sequence, ply thickness, and its location parameters affect the natural frequency values and the number of modes of the methods.Öğe Buckling and compressive failure of stepped-lap joints repaired with composite patches(SAGE PUBLICATIONS LTD, 2012) Beylergil, Bertan; Aktas, Alaattin; Cunedioglu, YusufIn this study, the buckling and compressive failure of adhesively-bonded stepped-lap joints (with/without composite patches) composed of pultruded glass fiber-reinforced polymer composite laminates was investigated experimentally and numerically. Two-component epoxy adhesive was used for bonding purposes. Composite patches were woven glass-epoxy layer. They were added onto the conventional stepped-lap joints so that additional load transfer paths were created and localized stress concentrations near joint edge were reduced. The axial compression tests were performed and the results revealed that the buckling and failure load of new stepped lap composite joints with composite patches were significantly higher than the conventional stepped lap joints. The influence of the overlap length was evaluated. For both types of joints, a small increase was observed in failure loads by increase of the overlap length. Numerical results showed a very good agreement with experimental results.Öğe Çatlaklı ankastre sandviç kirişlerin serbest titreşim analizi(2022) Cunedioglu, Yusuf; Devecioğlu, BurakBu çalışmada bir ucu ankastre diğer ucu serbest olan kompozit sandviç kirişlerin serbest titreşimi incelenmiştir. Çatlaklı ve çatlaksız halde sandviç kirişin doğal frekanslarının doğrulanması analitik ve ANSYS yazılım programı ile sağlandıktan sonra daha hızlı çözüm elde etmek adına analizler ANSYS programı ile gerçekleştirilmiştir. Çalışmada U ve V çatlak yapısının doğal frekans değerleri üzerindeki etkisi farklı çatlak konumlarında, farklı çatlak derinliklerinde ve farklı çatlak genişlikleri için incelenmiştir. Çalışmada 3 ve 5 tabakalı sandviç kirişler incelenmiştir. İncelenen bu parametrelerin kirişin doğal frekans değerlerini önemli ölçüde etkilediği gözlemlenmiştir.Öğe Enhancement of Single-Lap Composite Joints Strength at Different Temperatures(TAYLOR & FRANCIS LTD, 2012) Beylergil, Bertan; Cunedioglu, Yusuf; Aktas, AlaattinIn this study a novel reinforcing method was examined for glass-fiber reinforced composites consisted of inter-adherend glass fibers which acted as pins to pierce the composite adherend. Two types of inter-adherends were investigated. One of the types involved fibers which acted as pins (type B), and the other type was made up of pin like fibers with bent edges which stuck to the surface of the adherend (type C). Static tensile tests were performed on both types of single-lap joints (SLJ) and for joints without inter-adherend fibers (type A) at four different temperatures (20, 40, 60 and 80 degrees C) in accordance with ASTM standards. The results showed that the fibers improved the ultimate static strength of the single-lap joints over the entire temperature range. (C) Koninklijke Brill NV, Leiden, 2012Öğe Experimental and numerical analysis of single lap composite joints with inter-adherend fibers(ELSEVIER SCI LTD, 2011) Beylergil, Bertan; Cunedioglu, Yusuf; Aktas, AlaattinIn this study, a novel reinforcing method for glass-fiber reinforced composites, which consists of inter-adherend glass fibers (IAF) that get through the composite adherend like a pin, was investigated experimentally and numerically. Two types of joints were investigated. One is the traditional single lap joint without inter-adherend (Type A) and the other is Type B in which the fiber pin was used. Static tensile tests were performed at ambient environment in accordance with ASTM standards. In the numerical analysis, ANSYS 12.0 software package was used. The results show that the fibers improve the ultimate strength and damage tolerance of composite joints. In addition, the numerical results show a good agreement with the experimental ones. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Experimental and numerical failure analysis of pinned-joints in composite materials(ELSEVIER SCI LTD, 2009) Aktas, Alaattin; Imrek, Hueseyin; Cunedioglu, YusufIn this paper, failure load and failure mode of glass-epoxy composite plates with single and double parallel pinned-joints have analysed experimentally and numerically. Two variables were investigated during analyses; the distance from the free edge of plate to the diameter of the first hole (E/D) ratio (2, 3, 4, 5), and the width of the specimen to the diameter of the holes (W/D) ratios (2, 3, 4, 5). Experiments were carried out according to the ASTM D953-D [ASTM D 953-D, Standard test method for bearing strength of plastics, ASTM designation. p. 342-6.]. The numerical study was performed by means of ANSYS finite element analysis program. Yamada-Sun failure criterion was used for failure analyses. Mechanical properties of the composite material were obtained according to ASTM standards. The results showed that the pin hole farthest from the free edge is subjected to the highest stress. A good agreement was obtained between experimental results and numerical predictions. (C) 2008 Elsevier Ltd. All rights reserved.Öğe Free Vibration Analysis of a Functionally Graded Material Coated Aluminum Beam(Amer Inst Aeronautics Astronautics, 2020) Erdurcan, Ersoy Fatih; Cunedioglu, YusufThis paper presents a theoretical investigation on the free vibration of a symmetric beam consisting of an aluminum core coated with functionally graded material. The elastic modulus and density are varied throughout the thickness of the coating material with both a polynomial and an exponential function, whereas a classical lamination theory is applied to determine the effective elastic modulus and density. To model the gradually changing mechanical properties in a truthful way, the coating is represented by 25 layers of material, whereas each layer itself is homogeneous and isotropic. To obtain a numerical solution, the Timoshenko finite element model beam theory (which also takes first-order shear deformation effects into account) is used. For this purpose, a finite element code is written in MATLAB and the natural frequencies of the beam are found. A detailed parametric study is conducted to show the influences of the core thickness to beam height ratio (h/H), the beam span to height ratio (L/H), the exponential function and power law index n, and multiple boundary conditions on the natural beam frequencies. It was observed that the studied parameters had a significant effect on the natural frequencies.Öğe Free vibration analysis of a single edge cracked symmetric functionally graded stepped beams(Sage Publications Inc, 2020) Cunedioglu, Yusuf; Shabani, ShkelzenFree vibration analysis of a single edge cracked multi-layered symmetric sandwich stepped Timoshenko beams, made of functionally graded materials, is studied using finite element method and linear elastic fracture mechanic theory. The cantilever functionally graded beam consists of 50 layers, assumed that the second stage of the beam (step part) is created by machining. Thus, providing the material continuity between the two beam stages. It is assumed that material properties vary continuously, along the thickness direction according to the exponential and power laws. A developed MATLAB code is used to find the natural frequencies of three types of the stepped beam, concluding a good agreement with the known data from the literature, supported also by ANSYS software in data verification. In the study, the effects of the crack location, crack depth, power law gradient index, different material distributions, different stepped length, different cross-sectional geometries on natural frequencies and mode shapes are analysed in detail.Öğe Free vibration analysis of cracked functionally graded non-uniform beams(Iop Publishing Ltd, 2020) Shabani, Shkelzen; Cunedioglu, YusufThis paper presents the free vibration analysis of an edge cracked non-uniform symmetric beam made of functionally graded material. The Timoshenko beam theory is used for the finite element analysis of the multi-layered sandwich beam and the cantilever beam is modeled by 50 layers of material. The material properties vary continuously along the thickness direction according to the exponential and power laws. A MATLAB code is used to find the natural frequencies of two types of non-uniform beams, having a constant height but an exponential or linear width variation along the length of the beam. The natural frequencies of the beam are verified with ANSYS software as well as with available literature and good agreement is found. In the study, the effects of different parameters such as crack location, crack depth, power-law index, geometric index and taper ratio on natural frequencies are analyzed in detail.Öğe Free vibration analysis of damaged composite beams(TECHNO-PRESS, 2015) Cunedioglu, Yusuf; Beylergil, BertanIn this study, free vibration analyses of symmetric laminated cantilever and simply supported damaged composite beams are investigated by using finite element method (FEM). Free vibration responses of damaged beams are examined using Euler Bernoulli beam and classical lamination theories. A computer code is developed by using MATLAB software to determine the natural frequencies of a damaged beam. The local damage zone is assumed to be on the surface lamina of the beam by broken fibers after impact. The damaged zone is modeled as a unidirectional discontinuous lamina with 0 degrees orientations in this study. Fiber volume fraction (v(f)), fiber aspect ratio (L-f/d(f)), damage length (L-D) and its location (lambda/L), fiber orientation and stacking sequence parameters effects on natural frequencies are investigated. These parameters are affected the natural frequency values significantly.Öğe Free vibration analysis of edge cracked symmetric functionally graded sandwich beams(TECHNO-PRESS, 2015) Cunedioglu, YusufIn this study, free vibration analysis of an edge cracked multilayered symmetric sandwich beams made of functionally graded materials are investigated. Modelling of the cracked structure is based on the linear elastic fracture mechanics theory. Material properties of the functionally graded beams change in the thickness direction according to the power and exponential laws. To represent functionally graded symmetric sandwich beams more realistic, fifty layered beam is considered. Composition of each layer is different although each layer is isotropic and homogeneous. The considered problem is carried out within the Timoshenko first order shear deformation beam theory by using finite element method. A MATLAB code developed to calculate natural frequencies for clamped and simply supported conditions. The obtained results are compared with published studies and excellent agreement is observed. In the study, the effects of crack location, depth of the crack, power law index and slenderness ratio on the natural frequencies are investigated.Öğe Free Vibration Analysis of Functionally Graded Beams with Cracks(Shahid Chamran Univ Ahvaz, Iran, 2020) Shabani, Shkelzen; Cunedioglu, YusufThis study introduces the free vibration analysis of multilayered symmetric sandwich Timoshenko beams, made of functionally graded materials with two edge cracked, using the finite element method and linear elastic fracture mechanic theory. The FG beam consists of 50 layers, located symmetrically to the neutral plane, whose material properties distribution change along the beam thickness, according to power and exponential laws. The constituent of each layer of the beam is different, but each layer is isotropic and homogeneous. Natural frequency values of a cantilever beam are calculated using a developed MATLAB code. There is good agreement between the present results and the published results from the literature. A detailed study is carried out to observe the effect of crack location, crack depth ratio, power law index and material distribution on the first four natural frequencies.Öğe Free vibration analysis of laminated composite beam under room and high temperatures(TECHNO-PRESS, 2014) Cunedioglu, Yusuf; Beylergil, BertanThe aim of this study is to investigate the effects of the beam aspect ratio(L/h), hole diameter, hole location and stacking layer sequence ([0/45/-45/90](s), [45/0/-45/90](s) and [90/45/-45/0](s)) on natural frequencies of glass/epoxy perforated beams under room and high (40, 60, 80, and 100 degrees C) temperatures for the common clamped-free boundary conditions (cantilever beam). The first three out of plane bending free vibration of symmetric laminated beams is studied by Timoshenko's first order shear deformation theory. For the numerical analyses, ANSYS 13.0 software package is utilized. The results show that the hole diameter, stacking layer sequence and hole location have important effect especially on the second and third mode natural frequency values for the short beams and the high temperatures affects the natural frequency values significantly. The results are presented in tabular and graphical form.Öğe POROSİTELİ FDM İLE KAPLI ALÜMİNYUM KİRİŞİN SERBESTTİTREŞİMİNİN İNCELENMESİ(2020) Erdurcan, Ersoy Fatih; Cunedioglu, YusufBu çalışmada çekirdek tabakası alüminyum ve yüzeyleri porosite ihtiva eden fonksiyonel derecelendirilmiş malzeme (FDM)ile kaplı simetrik yapıda ankastre sandviç bir kirişin serbest titreşim analizi incelenmiştir. Fonksiyonel derecelendirilmiş malzemenin elastisite modülü ve yoğunluğu kirişin tabaka kalınlığı boyunca bir polinom fonksiyonla değiştiği kabul edilmiştir. FDM’yi gerçeğe yakın bir şekilde temsil etmek için kaplama kalınlığının 25 tabakadan oluştuğu ve her bir tabaka kendi içinde homojen izotrop olarak modellenmiştir. Bu yapılara ait efektif yoğunluk ve elastisite modülü tabakalı kompozit kiriş teorisi kullanılarak belirlenmiştir. Çalışmada birinci mertebe kayma deformasyonu içeren Timoshenko kiriş teorisi kullanılarak problemin çözümü sonlu elemanlar metoduyla gerçekleştirilmiştir. Kirişin doğal frekanslarının hesaplanması için MATLAB’ta sonlu elemanlar kodu yazılmıştır. Çalışmada porosite hacim oranının (a), çekirdek tabaka kalınlığının FDM kalınlık oranına(h/H), kiriş açıklığının yüksekliğine oranının (L/H) ve FDM’nin mekanik özelliklerini belirleyen polinom parametresinin (n) doğal frekansların üzerindeki etkisi incelenmiştir. İncelenen parametrelerin kirişin doğal frekanslarını önemli ölçüde etkilediği gözlemlenmiştir.
