Yazar "Avey, Mahmure" seçeneğine göre listele

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    An approach to the solution of nonlinear forced vibration problem of structural systems reinforced with advanced materials in the presence of viscous damping
    (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND, 2021) Sofiyev, Abdullah H.; Avey, Mahmure; Kuruoğlu, Nuri
    In this study, the nonlinear forced vibration of composite structural systems such as plates, panels and shells reinforced with advanced materials in the presence of linear viscous damping is investigated. Hamilton principle and von K´ arman-type ´ nonlinear theory are used to obtain the theoretical model of double-curved shells reinforced by carbon nanotubes (CNTs). The nonlinear partial differential equations are reduced to ordinary differential equations using Galerkin method. By using the multiscale method, the frequency-amplitude relation and nonlinear forced vibration frequency of structural systems are obtained for the first time. Since double-curved shells can be transformed into other structural systems such as spherical and hyperbolicparaboloid shells, rectangular plate and cylindrical panel in special cases, the expressions for nonlinear frequencies can also be used for them. In additional, the backbone curve and the nonlinear frequency/linear frequency ratio are determined as a function of the amplitude in primary resonance for the first time. The results are verified by comparing the reliability and accuracy of the proposed formulation with those in the literature. Finally, a systematic study is aimed at controlling the influence of nonlinearity and types of distribution of CNTs on the frequencies and their quantitative and qualitative variation in the presence of external excitation and viscous damping.
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    Free Vibration of Thin-Walled Composite Shell Structures Reinforced with Uniform and Linear Carbon Nanotubes: Effect of the Elastic Foundation and Nonlinearity
    (MDPI, ST ALBAN-ANLAGE 66, CH-4052 BASEL, SWITZERLAND, 2021) Avey, Mahmure; Tornabene, Francesco; Dimitri, Rossana; Kuruoğlu, Nuri
    In this work, we discuss the free vibration behavior of thin-walled composite shell structures reinforced with carbon nanotubes (CNTs) in a nonlinear setting and resting on a Winkler– Pasternak Foundation (WPF). The theoretical model and the differential equations associated with the problem account for different distributions of CNTs (with uniform or nonuniform linear patterns), together with the presence of an elastic foundation, and von-Karman type nonlinearities. The basic equations of the problem are solved by using the Galerkin and Grigolyuk methods, in order to determine the frequencies associated with linear and nonlinear free vibrations. The reliability of the proposed methodology is verified against further predictions from the literature. Then, we examine the model for the sensitivity of the vibration response to different input parameters, such as the mechanical properties of the soil, or the nonlinearities and distributions of the reinforcing CNT phase, as useful for design purposes and benchmark solutions for more complicated computational studies on the topic.
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    Influences of elastic foundations and thermal environments on the thermoelastic buckling of nanocomposite truncated conical shells
    (SPRINGER WIEN, SACHSENPLATZ 4-6, PO BOX 89, A-1201 WIEN, AUSTRIA, 2022) Avey, Mahmure; Sofiyev, Abdullah H.; Kuruoğlu, Nuri
    In this study, the combined effects of two-parameter elastic foundation and thermal environment on the buckling behaviors of carbon nanotube (CNT) patterned composite conical shells in the framework of the shear deformation theory (SDT) are investigated. It is assumed that the nanocomposite conical shell is freely supported at its ends and that the material properties are temperature dependent. The derivation of fundamental equations of CNT-patterned truncated conical shells on elastic foundations is based on the Donnell shell theory. The Galerkin method is applied to the basic equations to find the expressions for the critical temperature (CT) and axial buckling loads of CNT-patterned truncated conical shells on elastic foundations and in thermal environments. In the presence of elastic foundations and thermal environments, it is estimated how the effects of CNT patterns, the volume fractions, and the characteristics of conical shells on the buckling load within SDT change by comparing them with the classical shell theory (CST).
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    Influences of elastic foundations on the nonlinear free vibration of composite shells containing carbon nanotubes within shear deformation theory
    (ELSEVIER SCI LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND, 2022) Avey, Mahmure; Fantuzzi, Nicholas; Sofiyev, Abdullah H.; Kuruoğlu, Nuri
    In this work, the solution of nonlinear free vibration problem of composite shells structures containing carbon nanotubes (CNTs) resting on elastic soils within shear deformation theory (ST) is presented. After modeling the mechanical properties of nanocomposite shell structures containing CNTs and elastic soils, the basic relations, and governing equations of double curved shell structures within the ST are established considering the geometric nonlinearity. The frequencies of nonlinear and linear free vibrations and their ratios for inhomogeneous nanocomposite structures on the soils within the ST are obtained using perturbation method for the first time. After checking the methodology of the research, the effects of soils, nonlinearity, shear strains and patterns of CNT on the frequency-amplitude dependence of nanocomposite shell structures for various geometric parameters are carried out.
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    Nonlinear vibration of multilayer shell-type structural elements with double curvature consisting of CNT patterned layers within different theories
    (ELSEVIER SCI LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND, 2021) Avey, Mahmure; Fantuzzi, Nicholas; Sofiyev, Abdullah H.; Kuruoğlu, Nuri
    In this article, the nonlinear vibration of moderately thick multilayer shell?type structural elements with double curvature consisting of carbon nanotube (CNT) patterned layers is investigated within different shell theories. The first order shear deformation theory has been generalized on the motion for moderately thick multilayer shell?type structural elements with double curvature consisting of CNT patterned layers for the first time. Then, by applying Galerkin and semi?inverse perturbation methods to motion equations, and the frequency? amplitude relationship is obtained. From these formulas, the expressions for nonlinear frequencies of multilayer spherical and hyperbolic?paraboloid shells, rectangular plate and cylindrical panels patterned by CNTs within shear deformation and classical shell theories are obtained in special cases. The reliability of obtained results is verified by comparison with other results reported in the literature. The effects of transverse shear strains, volume fraction, sequence and number of nanocomposite layers on nonlinear frequency are discussed in detail.
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    Primary resonance of double-curved nanocomposite shells using nonlinear theory and multi-scales method: Modeling and analytical solution
    (PERGAMON-ELSEVIER SCIENCE LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND, 2021) Avey, Mahmure; Sofiyev, Abdullah H.; Fantuzzi, Nicholas; Kuruoğlu, Nuri
    In this article, the forced vibration of double-curved nanocomposite shells under a time dependent excitation is studied using nonlinear shell theory and multi-scales method in primary resonance. The nanocomposite representative volume element consists of two phases, including carbon nanotube (CNT) and matrix. By generalizing the Ambartsumyan’s first order shear deformation shell theory (FSDT) to the heterogeneous nanocomposite shells, the nonlinear partial differential equations are derived. Then, the problem is reduced to the nonlinear forced vibration of damped nanocomposite shells with quadratic and cubic nonlinearities. For the occurrence of the primary resonance, the damping, nonlinearity, and excitation terms in the disturbance circuit are reduced to the same order. Applying the multi-scales method to nonlinear ordinary differential equation, nonlinear frequency–amplitude dependence in primary resonance is obtained.