Yazar "Akbaş, Şeref Doǧuşcan" seçeneğine göre listele

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    Buckling Analysis of a Fiber Reinforced Laminated Composite Plate with Porosity
    (UNIV TEHRAN, 2019) Yüksel, Yusuf Ziya; Akbaş, Şeref Doǧuşcan
    Fiber-reinforced laminated composites are frequently preferred in many engineering projects. With the development in production technology, the using of the fiber reinforced laminated composites has been increasing in engineering applications. In the production stage of the fiber-reinforced laminated composites, porosities could be occurred due to production or technical errors. After a level of the porosity, the mechanical behaviors of composite materials change significantly. This paper presents buckling analysis of fiber-reinforced laminated composite plate with porosity effects within the first shear deformation plate theory. In the porosity effect, three different porosity models are used in the laminated composite plate. The material properties of the laminas are considered as orthotropic property. In the solution of the problem, the Navier procedure is used for the simply supported plate. Influences of the porosity coefficients, the porosity models, the fiber orientation angles and the sequence of laminas on the critical buckling loads are presented and discussed.
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    Damped forced vibration analysis of layered functionally graded thick beams with porosity
    (Techno-Press, 2021) Alnujaie A.; Akbaş, Şeref Doǧuşcan; Eltaher M.A.; Assie A.E.
    The following article presents the damped forced vibration of layered functionally graded thick beams including material porosities. In case of very thick beams, beam theories fail to satisfy boundary conditions and to predict the mechanical response accurately. So, the two-dimensional (2D) plane continuum model is exploited to model a thick functionally graded layered beam. The beam is composed from three- layers with functionally graded porous materials. The porosity is described by three different distribution models through the layer thickness. Applied forces to the functionally graded beam are assumed to be sinusoidal harmonic point load in time domain. The Kelvin-Voigt viscoelastic constitutive model is used to simulate damping effect. The governing equations are obtained by using Lagrange's equations. In frame of finite element analysis, twelve -node 2D plane element is exploited to discretize the space domain of thick beam. In the solution of the dynamic problem, the Newmark average acceleration method is used. Numerical studies illustrate effects of porosity distribution, stacking sequence, and graduation constant on the dynamic responses of layered functionally graded porous thick beams. The results show that the porosity function, stacking sequences and the damping ratio have a vital role in dynamic response of functionally graded beams. The proposed model can be used in nuclear, marine, and aerospace technologies.
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    Dynamic analysis of a fiber-reinforced composite beam under a moving load by the ritz method
    (MDPI AG, 2021) Akbaş, Şeref Doǧuşcan; Ersoy H.; Akgöz B.; Civalek Ö.
    This paper presents the dynamic responses of a fiber-reinforced composite beam under a moving load. The Timoshenko beam theory was employed to analyze the kinematics of the composite beam. The constitutive equations for motion were obtained by utilizing the Lagrange procedure. The Ritz method with polynomial functions was employed to solve the resulting equations in conjunction with the Newmark average acceleration method (NAAM). The influence of fiber orientation angle, volume fraction, and velocity of the moving load on the dynamic responses of the fiber-reinforced nonhomogeneous beam is presented and discussed.
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    Dynamic analysis of axially functionally graded porous beams under a moving load
    (2021) Akbaş, Şeref Doǧuşcan
    In presented paper, moving load problem of functionally graded beams is investigated with porosity effects based on the first shear beam theory. The material properties of beam vary along the axial direction. The porosity is depicted by two different distributions along axial direction. The governing equations of problem are derived by using the Lagrange procedure. In the solution of the problem the Ritz method is used and algebraic polynomials are used with the trivial functions for the Ritz method. In the solution of the moving load problem, the Newmark average acceleration method is used in the time history. In the numerical examples, the effects of material graduation, porosity distribution, porosity coefficients and velocity of moving load on the dynamic responses of axially functionally graded beam are presented and discussed. The dynamic responses are obtained for different boundary conditions.
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    Dynamic Analysis of Functionally Graded Porous Microbeams under Moving Load
    (Springer Science and Business Media B.V., 2022) Akbaş, Şeref Doǧuşcan; Dastjerdi S.; Akgöz B.; Civalek Ö.
    This paper presents dynamic analysis of a simply supported porous microbeam made of functionally graded materials subjected to a moving load. Material properties of the porous microbeam change in the thickness direction according to power-law distribution with different porosity models. The governing equations are obtained by Lagrange procedure based on Bernoulli–Euler beam and modified couple stress theories. Then, the resulting equations are solved by Ritz and Newmark average acceleration methods. A detailed parametric study is performed to investigate the effects of porosity coefficient, porosity distribution, material distribution, and length scale parameter on the dynamic responses of functionally graded porous microbeams.
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    Forced vibration analysis of a fiber reinforced composite beam
    (Techno-Press, 2021) Akbaş, Şeref Doǧuşcan
    In this study, forced vibration analysis of a fiber reinforced composite cantilever beam is investigated under a harmonic load. In the beam model, the Timoshenko beam theory is used. The governing equations of problem are derived by using the Lagrange procedure. In the solution of the problem the Ritz method is used and algebraic polynomials are used with the trivial functions for the Ritz method. In the solution of the forced vibration problem, the Newmark average acceleration method is used in the time history. In the numerical examples, the effects of fibre orientation angles, the volume fraction and dynamic parameters on the forced vibration response of fiber reinforced composite beam are presented and discussed.
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    Hygrothermal stress analysis of laminated composite porous plates
    (Techno-Press, 2021) Yüksel, Yusuf Ziya; Akbaş, Şeref Doǧuşcan
    This paper presents the stress analysis of a composite laminated simply supported plate with porosity under hygrothermal rising. In the displacement-strain relation of the plate structure, the first shear plate deformation theory is used. Material properties of laminas are considered as orthotropic. Three different porosity distributions are used. In the solution process, the Navier method is implemented for simply supported laminated composite plate. Non-uniform temperature and moisture rising are considered for laminated plate with three laminas. In the numerical results, the stress distributions of the laminated plate are presented and discussed for different values of moisture, temperature, stacking sequence of laminas and orientation angle of layers. The numerical results show that the hygrothermal condition is very effective in the stress behavior of laminated plates.
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    Moving-load dynamic analysis of AFG beams under thermal effect
    (Techno-Press, 2022) Akbaş, Şeref Doǧuşcan
    In presented paper, moving load problem of simply supported axially functionally graded (AFG) beam is investigated under temperature rising based on the first shear beam theory. The material properties of beam vary along the axial direction. Material properties of the beam are considered as temperature-dependent. The governing equations of problem are derived by using the Lagrange procedure. In the solution of the problem the Ritz method is used and algebraic polynomials are used with the trivial functions for the Ritz method. In the solution of the moving load problem, the Newmark average acceleration method is used in the time history. In the numerical examples, the effects of material graduation, temperature rising and velocity of moving load on the dynamic responses of AFG beam are presented and discussed.
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    Nonlinear dynamic and stability of a beam resting on the nonlinear elastic foundation under thermal effect based on the finite strain theory
    (Techno-Press, 2021) Alimoradzadeh M.; Akbaş, Şeref Doǧuşcan; Esfrajani S.M.
    Nonlinear free vibration and thermal buckling of a beam resting on nonlinear are investigated in this study. In the nonlinear kinematic relations, the finite strain theory is used with Euler-Bernoulli and Hamilton's principle is employed to derive the nonlinear governing of motion. The Galerkin's method is applied to simplify the governing nonlinear partially differential equation to the nonlinear ordinary differential equation. In addition, He's variational method is employed to obtain an analytical expression for the nonlinear natural frequency and thermal buckling temperature. In this study, a comparison between the finite strain theory and the von Kármán Theory is presented and the results shows that the finite strain theory gives more accurate results than the von Kármán Theory for nonlinear natural frequency and thermal buckling temperature. In the numerical results, the effect of different parameters such as linear and nonlinear coefficients of the elastic foundation, boundary conditions and the amplitude of the oscillation on the thermal buckling temperature and the nonlinear natural frequency investigated.