Yazar "Calim, Faruk Firat" 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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    Damped response of porous functionally graded viscoelastic cylindrical shells
    (Taylor & Francis Inc, 2024) Calim, Faruk Firat; Ozbey, Mehmet Bugra
    In this article, the behavior of viscoelastic porous functionally graded (FG) shells regarding the free and damped forced vibration analysis is investigated. The differential equations are derived by using higher order shear deformation theory. Using Hamilton's principle and the energy method, the equations of motion are obtained and solved using Navier's method. The damping effect is implemented into the analysis by means of Kelvin and linear standard viscoelastic models. With the correspondence principle, the transition from elastic material properties to viscoelastic material properties is achieved. First, a free vibration analysis is performed to verify the accuracy of the developed algorithm and obtained results are compared with the existing studies in the literature. Afterwards, a parametric study considering two different viscoelasticity models is performed. In the first parametric example, damped forced vibration analysis is performed for simply supported FG cylindrical shell using linear standard viscoelastic model as the viscoelastic model. Then, damped forced analysis is performed using Kelvin viscoelastic model for simply supported FG cylindrical shell. Analyses are performed in Laplace domain. The obtained results are transferred to time domain using Durbin's inverse Laplace transform method. The displacement graphs are given for the damped forced vibration examples. In the performed parametric studies, the effects of various porosity coefficients, ratios of instantaneous value, retardation times of the relaxation function and damping ratios on the analysis are investigated.
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    Dynamic response of curved Timoshenko beams resting on viscoelastic foundation
    (Techno-Press, 2016) Calim, Faruk Firat
    Curved beams' dynamic behavior on viscoelastic foundation is the subject of the current paper. By rewritten the Timoshenko beams theory formulation for the curved and twisted spatial rods, governing equations are obtained for the circular beams on viscoelastic foundation. Using the complementary functions method (CFM), in Laplace domain, an ordinary differential equation is solved and then those results are transformed to real space by Durbin's algorithm. Verification of the proposed method is illustrated by solving an example by variating foundation parameters.
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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 axially functionally graded Timoshenko beams on two-parameter viscoelastic foundation
    (Elsevier Sci Ltd, 2016) Calim, Faruk Firat
    The current study aims to analyze free and forced vibrations of axially functionally graded (AFG) Timoshenko beams on two-parameter viscoelastic foundation. in these kinds of beams, material properties alter through the axis. In the dynamic analysis, as research parameters, material inhomogeneity and foundation constants are considered. By using complementary functions method (CFM), in Laplace domain, differential equations are calculated. The calculations are performed in the Laplace domain. Calculations were transformed from Laplace domain to the time domain by applying Durbin's procedure. The free and forced vibrations of AFG Timoshenko beams on elastic/viscoelastic foundation are examined by solving different kinds of problems. The results obtained in this research showed that there is a relation and consistency with findings of the literature. (C) 2016 Elsevier Ltd. All rights reserved.
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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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    Transient analysis of axially functionally graded Timoshenko beams with variable cross-section
    (Elsevier Sci Ltd, 2016) Calim, Faruk Firat
    The present study goals to analyze transient analysis of axially functionally graded (AFG) Timoshenko beams with variable cross-section. Both the materials and geometrical properties of the AFG tapered beam varying along the longitudinal direction. In the analysis, the influences of rotary inertia and shear deformation are taken into account. Complementary functions method (CFM) is applied to solve the differential equations in Laplace domain. By using the modified Durbin's algorithm, the results are transformed to the time domain. For the verification of the recommended method, numerous problems which were solved in the literature are handled with the developed method and benchmarked with the findings in the literature. (C) 2016 Elsevier Ltd. All rights reserved.
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    Transient response of functionally graded non-uniform cylindrical helical rods
    (Techno-Press, 2021) Cuma, Yavuz C.; Calim, Faruk Firat
    This paper have the objective of investigating forced vibration behaviour of axially functionally graded cylindrical helices with variable cross-section. An algorithm is developed in order to solve corresponding problems. The ordinary differential equations governing the dynamic behaviour of cylindrical helices are determined in Laplace domain by using Timoshenko beam theory. Then transfer matrix method is implemented for the solution, including shear and axial deformation effects. Obtained results are transferred to time domain using Durbin's modified numerical inverse algorithm for Laplace transform. A benchmark problem has been solved to check the accuracy of developed algorithm then a parametric study is conducted considering the effects of material gradient index (beta(mat)), section variation (beta(sec)) and number of active turns (n). Results are compared with solutions attained from ANSYS for verification.
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    Vibration Analysis of Functionally Graded Timoshenko Beams on Winkler-Pasternak Elastic Foundation
    (Springer International Publishing Ag, 2020) Calim, Faruk Firat
    This paper aims to analyze dynamic response of axially functionally graded (FG) Timoshenko beams on Winkler-Pasternak elastic foundation. Spring constant and material inhomogeneity are used as research parameters in the dynamic analysis. In this study, ODEs in Laplace domain are calculated by using complementary functions method. The analysis is performed in the Laplace domain, and calculations are converted to the time domain by using Durbin's algorithm. The effects of material gradient index, translational and rotational spring constants, slenderness ratio, different boundary conditions and impulsive loads on the dynamic response of FG Timoshenko beams are investigated.
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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.