Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Polat, Alper(6)
- Onat, Onur(3)
- Kaya, Yusuf(2)
- Koçak, Ali(2)
- Lourenço, Paulo B.(2)
- Akkurt, Nevzat(1)
- Bendine, K.(1)
- Dalğıç, Aras(1)
- Eren, H.(1)
- Kaya, Fatih(1)
- Kaya, M.(1)
- Kaya, Y.(1)
- Kurum, Hasan(1)
- Kürüm, H.(1)
- Oksuztepe, Eyyup(1)
- Omac, Zeki(1)
- Omaç, Z.(1)
- Polat, A.(1)
- Polat, Elifcan Göçmen(1)
- Polat, Erkan(1)
- Polat, M.(1)
- Polat, Muhammed T.(1)
- Savaş, Sedat(1)
- Yakut, O.(1)
- Yıldırım, M.(1)
- Yılmazer Polat, Berivan(1)
- Öksüztepe, E.(1)
- Özsahin, Talat Sukru(1)
- Özşahin, T.Ş.(1)
Yayınlar
- MakaleAçık Erişim2026Scopus SJRQ2Experimental and numerical analysis of ceramic fiber geopolymer concrete under blast effect
Dalğıç, Aras; Yılmazer Polat, Berivan; Savaş, Sedat
This study employs both experimental and numerical methods to investigate the blast resistance of ceramic fiber-reinforced geopolymer concrete (CFGC), a cement-free material often referred to as green concrete due to its environmentally friendly nature compared to Portland cement concrete (PCC). Geopolymer concrete specimens, formulated with ground granulated blast furnace slag, silica fume, and varying proportions of ceramic fibers, were subjected to blast tests using 50, 100, 150, 200, and 250 grams of trinitroglycerin (TNG). A standard PCC specimen was utilized as a control. The results demonstrate that the incorporation of 10% ceramic fibers significantly enhances the blast resistance of the geopolymer concrete, reducing crater diameters by up to 20% compared to conventional PCC. Furthermore, the finite element model developed in ANSYS Workbench exhibits a strong correlation with the experimental data, validating the predictive capability of the numerical simulations. Overall, this research highlights the immense potential of CFGC as a sustainable, highly durable alternative for structures exposed to blast loads.
- MakaleYalnız künye2024Scopus SJRQ2Contact analysis in functionally graded layer loaded with circular two punches
Polat, Muhammed T.; Polat, Alper
In this study, contact analysis in a functionally graded (FG) layer loaded with two circular punches is solved using the finite element method (FEM). The problem is consisted of a functionally graded layer that resting on an elastic semi-infinite plane and is loaded with two rigid punches of circular geometry. External loads P and Q are transferred to the layer via two rigid punches. The finite element model of the functionally graded layer is created using the ANSYS package program and a 2-dimensional analysis of the problem is analyzed. The contact lengths, obtained as a result of the analysis are compared with the analytical solution in the literature. In the study, the effects of parameters such as distances between punches, loads, inhomogenity parameter on contact zones, initial separation loads and distances, normal stresses, stresses across depth and contact stresses are investigated. As a result, in this study, it can be said that the magnitude of the stresses occurring in the FG layer is less than the homogeneous layer, therefore the life of FG materials will be longer than the homogeneous layer. When the distance between the punches is 2.25, the initial separation distance is 6.98, and when the distance between the punches is 4, the initial separation distance decreases to 6.10. In addition, when the load increased in the second punch, the initial separation load decreased from 55 to 18. The obtained results are presented in the form of graphs and tables.
AtıfScopus1WoS1
İncele - MakaleYalnız künye2024Scopus SJRQ1Predicting and optimizing maximum flexural strength of planar composite plate shear walls – concrete filled with the application of LR and RSM
Polat, Erkan; Polat, Elifcan Göçmen
Traditional theoretical models, while conservative, overlook the complex, nonlinear interactions between material and geometric parameters that influence wall flexural strength. Additionally, the extent to which these models maintain their conservative assumptions across varying parameters remains uncertain. This study aims to develop advanced predictive models for the flexural strength of planar composite plate shear walls—concrete filled (C-PSW/CF) by employing Linear Regression (LR) and Response Surface Methodology (RSM). Central Composite Design (CCD) was utilized to design numerical experiments to analyze the effects of varying parameters, including steel plate yield strength, concrete compressive strength, wall depth, depth-to-thickness ratio, and reinforcement ratio. A validated complex finite element modeling (FEM) procedure was used to analyze numerical experiments involving varying parameters of the selected variables. Both LR and RSM were applied to the generated dataset to formulate predictive equations for the maximum moment capacity of walls. Interaction plots were developed to reveal the nonlinear relationships between the variables and identify the most effective parameters influencing the wall strength. Comparisons between theoretical predictions, RSM, and LR models revealed that RSM provided the most accurate predictions, closely aligning with FEM results and effectively capturing the nonlinear interactions between wall parameters. The findings of this paper contribute to the development of more practical, accurate and optimized design methods for C-PSW/CF, ultimately improving both structural safety and efficiency.
AtıfScopus10WoS8OpenAlex10İncele - MakaleYayıncıda açık erişim2023Estimation of Contact Lengths Using Deep Neural Network; [Derin Öğrenme Yöntemi ile Temas Uzunlukları Tahmini]
Polat, Alper
One of the most common problems in engineering is contact problems. In recent years, researchers have turned to alternative methods that can offer effective solutions in a shorter time, instead of solutions containing complex and long mathematical expressions. This study focuses on the estimation of the contact lengths in a homogeneous elastic layer suppressed by two elastic punches with two solution methods. Firstly, a new model was designed for estimation using Deep Learning Neural Network (DNN), one of the deep learning structures. Estimation of contact lengths was provided with the output of the DNN model, which was fed with the homogeneous elastic layer, the ratio of shear modules of the punches and the input parameters of punch radii. The finite element method was used as the second solution method. The problem was modelled in the ANSYS programme, and the solution was made with the same parameters used in DNN modelled. The results obtained from both solutions were compared with the solutions obtained by the theory of elasticity and classical NN in the literature. It had been seen that the results obtained with DNN and ANSYS were compatible with the results obtained with analytical and classical NN and the margin of error was smaller.
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İncele - MakaleAçık Erişim2023Scopus SJRQ2Stress analysis of the contact problem in a functionally graded layer loaded with a distributed load and two rigid circular punches resting on an elastic two quarter planes
Kaya, Fatih; Polat, Alper
In this study, the solution of the contact problem in a functionally graded (FG) layer resting on elastic two quarter planes was done using the finite element method (FEM). The contact problem consists of two rigid circular punches loaded FG and two elastic quarter planes. P and Q loads are transmitted to the FG layer by two rigid circular punches. All surfaces in the problem were considered as frictionless and the weight effect is also taken into account. The two-dimensional model of the contact problem was created with the ANSYS package program based on FEM and the stress analyzes were performed. All operations of quarter planes and circular punches are done with standard ANSYS menus. However, defining the material properties of the FG layer and dividing into meshes in finite elements cannot be done with standard menus. For this reason, a special macro was added to the program in order to define the material properties of the FG layer and to perform the mesh division, and the necessary parameters were applied to the layer by this macro. In the study, the effects of external load, stiffness parameter (βh), density parameter (γh) and contact stresses of distributed load change, normal stresses, and stresses along the depth were investigated.
AtıfScopus6WoS6OpenAlex5İncele - MakaleYalnız künye2022Scopus SJRQ1Analysis of discontinuous contact problem in two functionally graded layers resting on a rigid plane by using finite element method
Polat, Alper; Kaya, Yusuf
In this study, the problem of discontinuous contact in two functionally graded (FG) layers resting on a rigid plane and loaded by two rigid blocks is solved by the finite element method (FEM). Separate analyzes are made for the cases where the top surfaces of the problem layers are metal, the bottom surfaces are ceramic and the top surfaces are ceramic and the bottom surfaces are metal. For the problem, it is accepted that all surfaces are frictionless. A two-dimensional FEM analysis of the problem is made by using a special macro added to the ANSYS package program The solution of this study, which has no analytical solution in the literature, is given with FEM. Analyzes are made by loading different Q and P loads on the blocks. The normal stress (sigma y) distributions at the interfaces of FG layers and between the substrate and the rigid plane interface are obtained. In addition, the starting and ending points of the separations between these surfaces are determined. The normal stresses (sigma x, sigma y) and shear stresses (tau xy) at the point of separation are obtained along the depth. The results obtained are shown in graphics and tables. With this method, effective results are obtained in a very short time. In addition, analytically complex and long problems can be solved with this method.
AtıfWoS23İncele - MakaleYalnız künye2022Scopus SJRQ1Investigation of the effect of aspect ratio in an enclosure filled with phase change materials and its effect on thermal management of lithium-ion batteries: Applicable for storing solar energy
Akkurt, Nevzat
The numerical and transient behavior of a battery pack (BA-PK) consisting of three battery cells positioned within an air duct is investigated in this work. The BA-PK was connected to a solar system. The inside of the BA-PK is filled with phase change material. The air within the duct moved at a speed of 0.001–0.003 m/s around the BA-PK. The investigation was carried out by altering the dimensions of the BA-PK using COMSOL software. The finite element approach is used to solve the equations. The results of this research indicated that the battery temperature (Tbatt) drops gradually until the surrounding area is filled with molten PCM, but that once the PCM around the battery is entirely frozen, the Tbatt drops abruptly. The use of a larger BA-PK increases the temperature of the exhaust air out of the duct, but reduces the percentage of solid PCM. The Tbatt, as well as the maximum Tbatt and average TPCM within the compartment, are reduced by using a smaller BA-PK. In addition to increasing the quantity of solid PCM, increasing the speed lowers the temperatures of the batteries and PCM, as well as the temperature of the exhaust air.
AtıfScopus7WoS7OpenAlex7İncele - MakaleYalnız künye2021Scopus SJRQ2Examination of contact problem between functionally graded punch and functionally graded layer resting on elastic plane
Polat, Alper
In this study, continuous contact problem in the functionally graded (FG) layer loaded with a FG flat punch resting on the elastic semi-infinite plane was analyzed by the finite element method (FEM). It was assumed that the shear modulus and density of the layer and punch varied according to exponentially throughout their depth. FG layer's weight was included to the problem and additionally all surfaces were considered as frictionless. Analysis of FG materials was performed with a special macro which was added to the ANSYS program. Firstly, the shear modulus of the punch was considered to be very rigid and the results of initial separation load (λcr) and distance (xcr) were compared with the analytical solution. Afterwards, results obtained from the contact analysis made according to the inhomogeneity parameters (β, γ) between FG punch-FG layer which had been unprecedented in the literature were discussed. As a result, FG punch's stress values at the punch edges where stress accumulations occurred were found to be smaller than the rigid punch. The security of the structure, longer life of the material and ease of production are directly related to the reduction of the stress values. The results obtained in this study are important in this respect. Also this work is the first study that investigates the effect of FG punch on the FG layer.
AtıfScopus8WoS10OpenAlex2İncele - MakaleYalnız künye2019Scopus SJRQ1Fundamental vibration frequency prediction of historical masonry bridges
Onat, Onur
It is very common to find an empirical formulation in an earthquake design code to calculate fundamental vibration period of a structural system. Fundamental vibration period or frequency is a key parameter to provide adequate information pertinent to dynamic characteristics and performance assessment of a structure. This parameter enables to assess seismic demand of a structure. It is possible to find an empirical formulation related to reinforced concrete structures, masonry towers and slender masonry structures. Calculated natural vibration frequencies suggested by empirical formulation in the literatures has not suits in a high accuracy to the case of rest of the historical masonry bridges due to different construction techniques and wide variety of material properties. For the listed reasons, estimation of fundamental frequency gets harder. This paper aims to present an empirical formulation through Mean Square Error study to find ambient vibration frequency of historical masonry bridges by using a non-linear regression model. For this purpose, a series of data collected from literature especially focused on the finite element models of historical masonry bridges modelled in a full scale to get first global natural frequency, unit weight and elasticity modulus of used dominant material based on homogenization approach, length, height and width of the masonry bridge and main span length were considered to predict natural vibration frequency. An empirical formulation is proposed with 81% accuracy. Also, this study draw attention that this accuracy decreases to 35%, if the modulus of elasticity and unit weight are ignored.
AtıfWoS14OpenAlex6İncele - MakaleAçık Erişim2019Scopus SJRQ2Frictionless Contact Problem for a Functionally Graded Layer Loaded Through Two Rigid Punches Using Finite Element Method
Polat, A.; Kaya, Y.; Bendine, K.; Özşahin, T.Ş.
In this study, continuous contact problem in the functionally graded (FG) layer loaded with two rigid flat blocks resting on the elastic semi-infinite plane was analyzed by the finite element method. The two-dimensional numerical model of the FG layer was made with the software added to the ANSYS program. This software can be adapted to all contact problem types by making minor changes. The accuracy check of the program was performed by comparing with the analytical solution of the problem by homogeneous layer and its solution by the finite element method. So, fast and practical solutions can be obtained by the developed finite element method on many applications such as; automotive, aviation and space industry applications. The comparisons made showed that the proposed solution gave good results at acceptable levels. In the problem, it was thought that all surfaces were frictionless. The external loads P and Q were transmitted to the FG layer via two flat rigid blocks. Normal stresses between the FG layer and the elastic plane, initial separation loads, initial separation distances and contact stresses under the blocks were investigated for various dimensionless quantities.
AtıfScopus14WoS14OpenAlex11İncele - MakaleYalnız künye2018COMPARISON OF FEM SOLUTION WITH ANALYTICAL SOLUTION OF CONTINUOUS AND DISCONTINUOUS CONTACT PROBLEM
Kaya, Yusuf; Polat, Alper; Özsahin, Talat Sukru
The continuous and discontinuous contact problem of a homogeneous layer loaded with three rigid flat blocks and resting on the elastic semi-infinite plane was investigated in this study by using the finite element method (FEM). All surfaces are assumed to be frictionless. The homogenous layer was loaded by means of three rigid flat blocks whose external loads are Q and P (per unit thickness in z direction). Two dimensional finite element analysis of the problem was performed using ANSYS package program. Analyzes were performed for loading conditions which are Q=P, Q=2P, Q=4P, Q=8P and Q=10P, and different values of block widths, distances between blocks and shear modulus. The initial separation loads and initial separation distances (lambda(cr), chi(cr)) between the homogeneous layer and the elastic semi-infinite plane were determined for continuous contact condition. The length of the separation zone was obtained for discontinuous contact condition. In addition to these, normal stress distributions between the layer and the semi-infinite plane were determined for continuous and discontinuous contact conditions. As a result of the study, the analytical results, and the results of the finite element method were shown by comparing as graphs and tables.
AtıfWoS5İncele - MakaleAçık Erişim2018Scopus SJRQ3Design, analysis, and control of in-wheel switched reluctance motor for electric vehicles
Omaç, Z.; Polat, M.; Öksüztepe, E.; Yıldırım, M.; Yakut, O.; Eren, H.; Kaya, M.; Kürüm, H.
Estimation of dimension parameters for an electric machine has great importance before assembling on production line. As a matter of fact, researchers should find optimum solution once they decide to perform analytical design of an electric machine. In this study, we have tried to find dimensional and electrical parameters via derived mathematical equations for in-wheel switched reluctance motor (IW-SRM), and the motor has been manufactured. Moreover, an experimental setup is designed, and the speed and torque control of IW-SRM is carried out. The motor tests including both standstill and running test are performed by using the experimental setup. Initial size parameters are intuitively provided as motor analysis is conducted by software package. Then, numerous trials are examined to get optimum results. In fact, this motor is employed by an electric vehicle whose design is ongoing. Therefore, optimum motor parameters for required base speed and torque have been estimated by solving generated equations for IW-SRM with 18/12 poles via MATLAB. Considering parameters estimated, analysis of IW-SRM has been performed by Ansoft Maxwell 15.0 Software Package based on 3D finite element method (3D-FEM). Consequently, the estimated parameters have been validated by the results of Maxwell 3D FEM. Experimental results of the motor manufactured are obtained via the motor driver designed; also have been validated by Maxwell 3D.
AtıfScopus14WoS15OpenAlex24İncele - MakaleAçık Erişim2017Scopus SJRQ3Structural model calibration of RC structure with twoleaf cavity brick infill wall by deterministic approach
Onat, Onur; Lourenço, Paulo B.; Koçak, Ali
An adaptive solution for updating structural model of a RC structure with two-leaf cavity brick infill wall under flexible boundary problem is presented in this paper. The structure was simulated with Diana 9.4.4 finite element software. Next, an elastic foundation with interface elements was used to overcome this stiffness problem of the foundation. The validation of the structure was made with the optimization based modal updating using MATLAB. Five calibration types were performed and compared with experimental data.
AtıfScopus8WoS8OpenAlex6İncele - MakaleYalnız künye2015Scopus SJRQ2Experimental and numerical analysis of RC structure with two leaf cavity wall subjected to shake table
Onat, Onur; Lourenço, Paulo B.; Koçak, Ali
This paper presents finite element (FE) based pushover analysis of a reinforced concrete structure with a two-leaf cavity wall (TLCW) to estimate the performance level of this structure. In addition to this, an unreinforced masonry (URM) model was selected for comparison. Simulations and analyses of these structures were performed using the DIANA FE program. The mentioned structures were selected as two storeys and two bays. The dimensions of the structures were scaled 1: 1.5 according to the Cauchy Froude similitude law. A shake table experiment was implemented on the reinforced concrete structure with the two-leaf cavity wall (TLCW) at the National Civil Engineering Laboratory (LNEC) in Lisbon, Portugal. The model that simulates URM was not experimentally studied. This structure was modelled in the same manner as the TLCW. The purpose of this virtual model is to compare the respective performances. Two nonlinear analyses were performed and compared with the experimental test results. These analyses were carried out in two phases. The research addresses first the analysis of a structure with only reinforced concrete elements, and secondly the analysis of the same structure with reinforced concrete elements and infill walls. Both researches consider static loading and pushover analysis. The experimental pushover curve was plotted by the envelope of the experimental curve obtained on the basis of the shake table records. Crack patterns, failure modes and performance curves were plotted for both models. Finally, results were evaluated on the basis of the current regulation ASCE/SEI 41-06.
AtıfWoS15İncele - MakaleÖn baskısı açık2014Scopus SJRQ3Sensorless vector control of PMSM with non-sinusoidal flux using observer based on FEM
Oksuztepe, Eyyup; Omac, Zeki; Kurum, Hasan
Back electromotive force method has been widely used in the position and speed sensorless control of permanent magnet synchronous motors. In this method, it is supposed that the back electromotive forces induced on the stator windings by the rotor permanent magnets are sinusoidal. This assumption causes errors in the estimation of speed and position. In this paper, an observer using the stator winding linkage flux model obtained by using finite element method for position and speed sensorless field-oriented control of permanent magnet motor is proposed. The validity of the proposed method is demonstrated using DS 1104.
AtıfWoS11OpenAlex12İncele