Yazar "Cuma, Yavuz Cetin" seçeneğine göre listele

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    An Efficient Approach for Free Vibration Behaviour of Non-Uniform and Non-Homogeneous Helices
    (Springer Int Publ Ag, 2023) Turker, Hakan Tacattin; Cuma, Yavuz Cetin; Calim, Faruk Firat
    The paper presents an efficient numerical method for free vibration analysis of non-uniform and non-homogeneous cylindrical helices. Power law distribution is used for the variation of the material properties along the axial direction of rods. The derivation of the governing equations are carried out by the Timoshenko's beam theory. Obtained ordinary differential equations of the problems are solved using the complementary functions and stiffness matrix methods. Numerical examples are given to highlight the effects of varying geometric and material properties on free vibration. Proposed method requires a small number of elements in order to yield agreeable results. The computed results are compared with those reported in the literature and obtained from the finite element ANSYS software.
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    Dynamic analysis of viscoelastic FGM shells with porosities on elastic foundation
    (Techno-Press, 2024) Calim, Mehmet Halil; Capar, Omer Faruk; Ozbey, Mehmet Bugra; Cuma, Yavuz Cetin
    This study investigates free and damped vibration behaviours of porous functionally graded shells supported by Winkler-Pasternak foundation, considering different geometries. Utilizing a higher-order shear deformation theory, the displacement field is determined. The equations of motion are formulated using Hamilton's principle, and the solutions are obtained Navier's method employing double Fourier series. Parametric studies regarding the effects of porosity, material distribution, elastic foundation, shell geometry and damping are carried out. Results are given in tabular and graphical form for the free and forced vibration analyses, respectively.
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    Dynamic analysis of viscoelastic porous functionally graded plates resting on elastic foundation
    (Techno-Press, 2024) Capar, oemer Faruk; Calim, Mehmet Halil; Ozbey, Mehmet Bugra; Cuma, Yavuz Cetin
    In this study, free and forced vibration behaviour of viscoelastic porous functionally graded (VPFG) plates resting on elastic foundations are investigated. Differential equations are obtained via higher order shear deformation theory. Equations of motion are obtained through energy formulations and Hamilton's principle. Navier's method based on double Fourier series is employed for the solution. Damping effect is implemented into the analysis by means of Kelvin and linear standard viscoelastic models. Viscoelastic material properties are used instead of elastic properties by means of the correspondence principle. Displacements of the plates are determined in Laplace domain and transformed into time domain by using Durbin's Modified Inverse Laplace transform method. The proposed algorithm's accuracy is validated through free and damped vibration analyses on VPFG plate, with results compared to existing studies in the literature. The study examines the influence of viscoelastic damping parameters, porosity volume fraction indexes, foundation characteristics, porosity distribution patterns and material property variations on the damped forced vibration response.
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    Dynamic response of viscoelastic functionally graded barrel and hyperboloidal coil springs with variable cross-sectional area
    (Springer, 2022) Cuma, Yavuz Cetin; Calim, Faruk Firat
    This paper investigates the dynamic response of viscoelastic axially functionally graded (AFG) barrel and hyperboloidal coil springs with variable cross-sectional area. Equations governing the dynamic behaviour of spatial rods are obtained via Timoshenko beam theory. The viscoelastic characteristics of the material are described by Kelvin's model. The transfer matrix method and stiffness matrix methods are used in combination in the numerical solution of the problem. Stiffness matrices are determined by the transfer matrix method (TMM). Solutions are obtained in the Laplace domain; the results are transformed into the time domain by Durbin's inverse Laplace transform algorithm. A benchmark solution for verifying non-cylindrical geometry is successfully integrated into the damped forced vibration analysis. A parametric study is conducted in which cylinder radius ratio, damping ratio, material gradient and cross-sectional area are varied for both helical rod geometries mentioned above.
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    Forced vibration analysis of viscoelastic helical rods with varying cross-section and functionally graded material
    (Taylor & Francis Inc, 2023) Calim, Faruk Firat; Cuma, Yavuz Cetin
    In scope of this study, forced vibration analysis of viscoelastic helical rods with varying cross-section and functionally graded material are investigated. Differential equations governing the dynamic behavior of helical rods are obtained in Laplace domain by the Timoshenko's beam theory. Material and section geometry are assumed to be varying functionally along the rod axis. Viscoelasticity of the material is implemented via Kelvin's model. Stiffness and transfer matrix methods are used together in order to obtain dynamic stiffness matrix of the system. Acquired results in Laplace domain are converted to time domain by using Durbin's inverse Laplace algorithm. A parametric study is carried out for the investigation of the effects of material variation, non-uniformity and damping on the forced vibration of functionally graded viscoelastic rods.
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    Free and forced vibration analysis of FG-CNTRC viscoelastic plate using high shear deformation theory
    (Techno-Press, 2024) Ozbey, Mehmet Bugra; Cuma, Yavuz Cetin; Deneme, Ibrahim Ozgur; Calim, Faruk Firat
    This paper investigates the dynamic behavior of a simply supported viscoelastic plate made of functionally graded carbon nanotube reinforced composite under dynamic loading. Carbon nanotubes are distributed in 5 different shapes: U, V, A, O and X, depending on the shape they form through the thickness of the plate. The displacement fields are derived in the Laplace domain using a higher -order shear deformation theory. Equations of motion are obtained through the application of the energy method and Hamilton's principle. The resulting equations of motion are solved using Navier's method. Transforming the Laplace domain displacements into the time domain involves Durbin's modified inverse Laplace transform. To validate the accuracy of the developed algorithm, a free vibration analysis is conducted for simply supported plate made of functionally graded carbon nanotube reinforced composite and compared against existing literature. Subsequently, a parametric forced vibration analysis considers the influence of various parameters: volume fractions of carbon nanotubes, their distributions, and ratios of instantaneous value to retardation time in the relaxation function, using a linear standard viscoelastic model. In the forced vibration analysis, the dynamic distributed load applied to functionally graded carbon nanotube reinforced composite viscoelastic plate is obtained in terms of double trigonometric series. The study culminates in an examination of maximum displacement, exploring the effects of different carbon nanotube distributions, volume fractions, and ratios of instantaneous value to retardation times in the relaxation function on the amplitudes of maximum displacements.
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    Free vibration analysis of functionally graded cylindrical helices with variable cross-section
    (Academic Press Ltd- Elsevier Science Ltd, 2021) Cuma, Yavuz Cetin; Calim, Faruk Firat
    The main purpose of this study is to investigate free vibrations of cylindrical helical rods with variable cross-section, composed of functionally graded materials, which may be used to model environmental effects. The material variation is considered to be along the rod axis. Governing differential equations of the free vibration are obtained via Timoshenko's beam theory, where axial and shear deformations and rotary inertia are taken into consideration. The governing equations are solved numerically by using the transfer matrix method. The effects of cross-section variation (beta(sec)), material gradient index (beta(mat)), helix pitch angle (alpha), and number of active coils (n) on the frequencies are investigated. All results are compared with the ANSYS solutions, in which a very well approximation is achieved. (C) 2020 Elsevier Ltd. All rights reserved.
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    Vibration analysis of nonuniform hyperboloidal and barrel helices made of functionally graded material
    (Taylor & Francis Inc, 2022) Calim, Faruk Firat; Cuma, Yavuz Cetin
    This study is in investigation of free vibration behavior of functionally graded hyperboloidal and barrel helices with variable cross section. Material and geometric variations of noncylindrical helices are assumed to be along the rod axis. Governing differential equations of motion, including rotatory inertia, axial and shear deformations are derived by the Timoshenko beam theory. Then, transfer matrix and stiffness matrix methods are employed for the numerical solution of obtained ordinary differential equations. Effects of material gradient index (beta(mat)), diameter variation parameter (beta(sec)), and ratio of helix radius at end section and middle section R-2/R-1 on the natural frequencies are investigated through a parametric study considering barrel and hyperboloidal geometries. Comparisons with available literature studies and ANSYS solutions are made regarding obtained results.
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    Vibration and damping analysis of functionally graded shells
    (Springer, 2024) Cuma, Yavuz Cetin; Ozbey, Mehmet Bugra; Calim, Faruk Firat
    In this study, dynamic behaviour of viscoelastic functionally graded shells under time-varying load is investigated. Displacement field is obtained by using higher order shear deformation theory. Equations of motion are obtained in Laplace domain by using the energy method. The equations of motion are solved by the Navier's method. Results are transferred to time domain by implementing Durbin's inverse Laplace algorithm. A parametric study of the damped forced vibration of functionally graded shells considering the effects of shell geometry, rate of material variation, the principal radii of curvature, viscoelastic parameters is carried out. Damping behaviour is investigated via linear standard viscoelastic model. Accuracy of the results are verified by comparison with the literature results.