Browsing by Subject "DYNAMIC-ANALYSIS"

Now showing 1 - 5 of 5
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    Application of Modified Couple-Stress Theory to Nonlinear Vibration Analysis of Nanobeam with Different Boundary Conditions
    (SPRINGER HEIDELBERG) Togun, N; Bagdatli, SM
    Purpose In the present study, the nonlinear vibration analysis of a nanoscale beam with different boundary conditions named as simply supported, clamped-clamped, clamped-simple and clamped-free are investigated numerically.Methods Nanoscale beam is considered as Euler-Bernoulli beam model having size-dependent. This non-classical nanobeam model has a size dependent incorporated with the material length scale parameter. The equation of motion of the system and the related boundary conditions are derived using the modified couple stress theory and employing Hamilton's principle. Multiple scale method is used to obtain the approximate analytical solution.Result Numerical results by considering the effect of the ratio of beam height to the internal material length scale parameter, h/l and with and without the Poisson effect, upsilon are graphically presented and tabulated.Conclusion We remark that small size effect and poisson effect have a considerable effect on the linear fundamental frequency and the vibration amplitude. In order to show the accuracy of the results obtained, comparison study is also performed with existing studies in the literature.
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    Investigation of nonlinear vibration behavior of the stepped nanobeam
    (TECHNO-PRESS) Nalbant, MO; Bagdatli, SM; Tekin, A
    Nonlinearity plays an important role in control systems , the application of design. For this reason, in addition to linear vibrations, nonlinear vibrations of the stepped nanobeam are also discussed in this manuscript. This study investigated the vibrations of stepped nanobeams according to Eringen's nonlocal elasticity theory. Eringen's nonlocal elasticity theory was used to capture the nanoscale effect. The nanoscale stepped Euler Bernoulli beam is considered. The equations of motion representing the motion of the beam are found by Hamilton's principle. The equations were subjected to nondimensionalization to make them independent of the dimensions and physical structure of the material. The equations of motion were found using the multi-time scale method, which is one of the approximate solution methods, perturbation methods. The first section of the series obtained from the perturbation solution represents a linear problem. The linear problem's natural frequencies are found for the simple -simple boundary condition. The second-order part of the perturbation solution is the nonlinear terms and is used as corrections to the linear problem. The system's amplitude and phase modulation equations are found in the results part of the problem. Nonlinear frequency-amplitude , external frequency-amplitude relationships are discussed. The location of the step, the radius ratios of the steps, and the changes of the small-scale parameter of the theory were investigated and their effects on nonlinear vibrations under simple-simple boundary conditions were observed by making comparisons. The results are presented via tables and graphs. The current beam model can assist in designing and fabricating integrated such as nano-sensors and nano -actuators.
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    Size dependent nonlinear vibration of the tensioned nanobeam based on the modified couple stress theory
    (ELSEVIER SCI LTD) Togun, N; Bagdatli, SM
    This paper presents a nonlinear vibration analysis of the tensioned nanobeams with simple simple and clamped clamped boundary conditions. The size dependent Euler Bernoulli beam model is applied to tensioned nanobeam. Governing differential equation of motion of the system is obtain by using modified couple stress theory and Hamilton's principle. The small size effect can be obtained by a material length scale parameter. The nonlinear equations of motion including stretching of the neutral axis are derived. Damping and forcing effects are considered in the analysis. The closed form approximate solution of nonlinear equations is solved by using the multiple scale method, a perturbation technique. The frequency-response curves of the system are constructed. Moreover, the effect of different system parameters on the vibration of the system are determined and presented numerically and graphically. The size effect is significant for very thin beams whose height is at the nanoscale. The vibration frequency predicted by the modified couple stress theory is larger than that by the classical beam theory. Comparison studies are also performed to verify the present formulation and solutions. (C) 2016 Elsevier Ltd. All rights reserved.
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    Stress and rigidity comparison and improved vibration control of flexible carbon-fiber and epoxy-glass composite manipulators under end-point load
    (IOP PUBLISHING LTD) Yavuz, S; Ilman, MM
    This paper presents the vibration control problem of the single-link flexible composite manipulators. Two different materials of composite which are epoxy-glass and carbon-fiber are considered for both simulation and experimental analyses. Manipulators are obliged to perform a job such as pick and place applications and machining a workpiece. Therefore, a payload is attached to the manipulators. If the system is suitable for loading applications, the improved vibration control method is used to suppress the residual vibrations of the manipulators. The simulation results are verified with experimental results and it is observed that the proposed vibration control method significantly reduces the residual vibrations compared to passive vibration control method in literature. Additionally, the stresses during motion are analyzed for both simulation and experiment and the effectiveness of the proposed method on the stresses is investigated. Results showed that only the carbon-fiber manipulator is suitable for payload applications and its utilization efficiency can be greatly improved by the proposed method.
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    Non-Linear Vibrations of a Microbeam Resting on an Elastic Foundation
    (SPRINGER HEIDELBERG) Sari, G; Pakdemirli, M
    In this study, response of a microbeam bonded to a non-linear elastic foundation is investigated. The model accounts for mid-plane stretching, an applied axial load, and an AC harmonic force. The microbeam is resting on a non-linear elastic foundation which introduces a cubic non-linear term to the equations of motion. Immovable end conditions introduce integral type nonlinearity. The integro-differential equations of motion are solved analytically by means of direct application of the method of multiple scales (a perturbation method). The amplitude and phase modulation equations are derived for the case of primary resonances. Frequency-response curves and non-linear frequencies are analyzed with respect to the effective physical parameters. Influence of elastic foundation coefficients, coefficients related to dielectric constants, and mid-plane stretching on the vibrations of the microbeam are investigated.