Moving-load dynamic analysis of AFG beams under thermal effect

Ş.D. Akbaş 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.5

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 ofAFG beam are presented and discussed.

Size dependent vibration of laminated micro beams under moving load

Ş.D. Akbaş 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.2

The goal of this paper is to investigate dynamic responses of simply-supported laminated micro beams under moving load. In the considered micro-scale problem, the modified coupled stress theory which includes the length scale parameter 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 moving load problem, the Newmark average acceleration method is used in the time history. In the numerical examples, the effects of stacking sequence of laminas, fibre orientation angles and the length scale parameter on the dynamic responses of laminated micro beams are examined and discussed.

Dynamic analysis of axially functionally graded porous beams under a moving load

Ş.D. Akbaş 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.39 No.6

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.

Nonlinear dynamic and stability of a beam resting on the nonlinear elastic foundation under thermal effect based on the finite strain theory

M. Alimoradzadeh,Ş.D. Akbaş,S.M. Esfrajani 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.3

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.

Nonlinear thermal vibration of FGM beams resting on nonlinear viscoelastic foundation

M. Alimoradzadeh,Ş.D. Akbaş 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.4

Nonlinear free vibration analysis of a functionally graded beam resting on the nonlinear viscoelastic foundation is studied with uniform temperature rising. The non-linear strain-displacement relationship is considered in the finite strain theory. The governing nonlinear dynamic equation is derived based on the finite strain theory with using of Hamilton’s principle. The Galerkin’s decomposition technique is utilized to discretize the governing nonlinear partial differential equation to nonlinear ordinary differential equation and then is solved by using of multiple time scale method. The influences of temperature rising, material distribution parameter, nonlinear viscoelastic foundation parameters on the nonlinear free response and phase trajectory are investigated. In this paper, it is aimed that a contribution to the literature for nonlinear thermal vibration solutions of a functionally graded beam resting on the nonlinear viscoelastic foundation by using of multiple time scale method.

Nonlinear free vibration analysis of a composite beam reinforced by carbon nanotubes

M. Alimoradzadeh,Ş.D. Akbaş 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.3

This investigation presents nonlinear free vibration of a carbon nanotube reinforced composite beam based on the Von Kármán nonlinearity and the Euler-Bernoulli beam theory The material properties of the structure is considered as made of a polymeric matrix by reinforced carbon nanotubes according to different material distributions. The governing equations of the nonlinear vibration problem is delivered by using Hamilton’s principle and the Galerkin’s decomposition technique is utilized to discretize the governing nonlinear partial differential equation to nonlinear ordinary differential equation and then is solved by using of multiple time scale method. The nonlinear natural frequency and the nonlinear free response of the system is obtained with the effect of different patterns of reinforcement.

Thermal nonlinear dynamic and stability of carbon nanotube-reinforced composite beams

M. Alimoradzadeh,Ş.D. Akbaş 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.5

Nonlinear free vibration and stability responses of a carbon nanotube reinforced composite beam under temperature rising are investigated in this paper. The material of the beam is considered as a polymeric matrix by reinforced the single-walled carbon nanotubes according to different distributions with temperature-dependent physical properties. With using the Hamilton’s principle, the governing nonlinear partial differential equation is derived based on the Euler-Bernoulli beam theory. In the nonlinear kinematic assumption, the Von Kármán nonlinearity is used. The Galerkin’s decomposition technique is utilized to discretize the governing nonlinear partial differential equation to nonlinear ordinary differential equation and then is solved by using of multiple time scale method. The critical buckling temperatures, the nonlinear natural frequencies and the nonlinear free response of the system is obtained. The effect of different patterns of reinforcement on the critical buckling temperature, nonlinear natural frequency, nonlinear free response and phase plane trajectory of the carbon nanotube reinforced composite beam investigated with temperature-dependent physical property.

Dynamic responses of functionally graded and layered composite beams

O. Kırlangıç,Ş.D. Akbaş 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.1

This paper presents and compares the free and damped forced vibrations of layered and functionally graded composite beams. In the considered study, a cantilever beam subjected to a harmonic point load at the free end is investigated with layered and functionally graded materials. In the kinematics of the beam, 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. Algebraic polynomials are used with the trial functions for the Ritz method. In the obtaining of free vibration results, the eigenvalue procedure is implemented. In the solution of the damped forced vibration problem, the Newmark average acceleration method is used in the time history. In the damping effect, the Kelvin-Voigt viscoelastic model is used with the constitutive relations. In the numerical examples, the effects of material distribution parameter and dynamic parameters on the natural frequencies and forced vibration responses of functionally graded beams are obtained and compared with the results of the layered composite beam. Also, comparison studies are performed in order to validate the used formulations.

Nonlinear dynamic responses of cracked atomic force microscopes

M. Alimoradzadeh,Ş.D. Akbaş 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.82 No.6

This study presents the nonlinear free and forced vibrations of a cracked atomic force microscopy (AFM) cantilever by using the modified couple stress. The cracked section of the AFM cantilever is considered and modeled as rotational spring. In the frame work of Euler-Bernoulli beam theory, Von-Karman type of geometric nonlinear equation and the modified couple stress theory, the nonlinear equation of motion for the cracked AFM is derived by Hamilton’s principle and then discretized by using the Galerkin’s method. The semi-inverse method is utilized for analysis nonlinear free oscillation of the system. Then the method of multiple scale is employed to investigate primary resonance of the system. Some numerical examples are presented to illustrate the effects of some parameters such as depth of the crack, length scale parameter, Tip-Mass, the magnitude and the location of the external excitation force on the nonlinear free and forced vibration behavior of the system.

Nonlinear dynamic behavior of functionally graded beams resting on nonlinear viscoelastic foundation under moving mass in thermal environment

M. Alimoradzadeh,Ş.D. Akbaş 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.81 No.6

The aim of this paper is to investigate nonlinear dynamic responses of functionally graded composite beam resting on the nonlinear viscoelastic foundation subjected to moving mass with temperature rising. The non-linear strain-displacement relationship is considered in the finite strain theory and the governing nonlinear dynamic equation is obtained by using the Hamilton’s principle. The Galerkin’s decomposition technique is utilized to discretize the governing nonlinear partial differential equation to nonlinear ordinary differential equation and then the governing equation is solved by using of multiple time scale method. The influences of temperature rising, material distribution parameter, nonlinear viscoelastic foundation parameters, magnitude and velocity of the moving mass on the nonlinear dynamic responses are investigated. Also, the buckling temperatures of the functionally graded beams based on the finite strain theory are obtained.