Fonksiyonel Değişimli Malzemelerle Kaplanmış Metal Silindirik Kabukların Serbest Titreşimi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2013Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2013İç ve dış yüzeyleri fonksiyonel değişimli malzemelerle (FDM’ler) kaplı metal silindirik kabukların serbest titreşim problemi incelenmektedir. FDM kaplı metal silindirik kabukların temel bağıntıları ve değiştirilmiş Donnell tipi temel denklemleri türetilmekte ve Galerkin Yöntemi uygulanarak çözülmektedir. FDM kaplı metal silindirik kabukların serbest titreşiminin boyutsuz frekans parametresi için analitik ifade bulunmaktadır. Analizler kısmında, kaplamalı silindirik kabukların serbest titreşimlerinin boyutsuz frekans parametrelerinin minimum değerlerine, hacim bileşenleri değişiminin, kabuk karakteristiklerinin, iç ve dış tabakaların kalınlıkları değişiminin etkileri sayısal olarak incelenmektedir. Anahtar Kelimeler: Fonksiyonel değişimli malzeme (FDM), Fonksiyonel değişimli (FD) kaplama, metal silindirik kabuk, serbest titreşim, boyutsuz frekans parametresiThe free vibration problem of the metal cylindrical shell coated with functionally graded materials (FGMs) in the inner and outer surfaces is investigated. The basic relations and modified Donnell type basic equations of metal cylindrical shells coated with FGMs are derived and solved by using Galerkin method. Analytical expression for the dimensionless frequency parameter of the metal cylindrical shell coated with FGMs is found. Finally, the effects of variations of volume fractions, shell characteristics and variations of the thickness of inner and outer coatings on the values of the dimensionless frequency parameters of free vibrations for coated cylindrical shells are studied numerically

Effects of material non-homogeneity and two parameter elastic foundation on fundamental frequency parameters of Timoshenko beams

In the present study, effects of material non-homogeneity and two-parameter elastic foundation on the fundamental frequency parameters of the simply supported beams are examined. Material non-homogeneity is characterized taking into account the parabolic variations of Young's modulus and density along the thickness direction of the beam while the value of Poisson's ratio is assumed to remain constant. The foundation medium is assumed to be linear, homogeneous and isotropic, and it is modeled by the Pasternak model with two parameters for describing the reaction of the elastic foundation on the beam. At first, the equation of the motion including the effects of the material non-homogeneity and two-parameter elastic foundation is provided. Then, the solutions including fundamental frequency parameters versus various non-homogeneity, density and foundation parameters, and length to depth ratio adopting the Timoshenko beam theory as well as the Euler-Bernoulli beam theory are presented. To show the accuracy of the present results, a comparison is carried out and a good agreement is found

Effects of the Non-Homogeneity and Elastic Medium on the Critical Torsional Load of the Orthotropic Cylindrical Shell footnotemark

In this study, the torsional stability problem of non-homogeneous orthotropic composite cylindrical shells in the elastic medium, using the Galerkin method was investigated. The Winkler model is used to describe the reaction of the elastic medium on the cylindrical shell. Mixed boundary conditions are considered. The effects of variations of shell parameters, non-homogeneity, orthotropy and foundation stiffness on the critical torsional load are examined

The stability of a three-layered composite conical shell containing a FGM layer subjected to external pressure

In this study, the stability of a generic three-layered truncated conical shell containing a functionally graded (FG) layer subjected to uniform external pressure is investigated. The material properties of the functionally graded layer are assumed to vary continuously through the thickness of the shell. The variation of the properties follows an arbitrary distribution in terms of the volume fractions of the constituents. The fundamental relations, the stability and compatibility equations of three-layered truncated conical shells containing a FG layer are obtained, first. Then, applying Galerkin's method, the closed form solution for critical external pressure is obtained. The results show that the critical parameters are affected by the configurations of the constituent materials, the variations of the thickness of the FG layer and the variation of the shell geometry. Comparing the results with those in the literature validates the present analysis

Elastik Zemin Üzerinde Bulunan Fonksiyonel Değişimli Tabaka İçeren Katmanlı Silindirik Kabukların Uniform Yanal Basınç Yükü Etkisi Altında Burkulması

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2010Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2010Bu çalışmada, basit mesnetli, Winkler zemini üzerinde bulunan, seramik, fonksiyonel degi§imli malzeme (FDM) ve metal tabakadan olusan tiç katmanlı kompozit silindirik kabuklanrı tiniform yanal basmç yükü etkisi altina burkulmasl incelenmektedir. FDM özellikleri kalınlık dogrultusunda kuvvet fonksiyonu seklinde degismektedir. Elastik zemin üzerinde bulunan FDM tabaka içeren üç katmanll silindirik kabuklar için temel denklemler elde edilir. Galerkin yöntemi uygulanarak kritik yanal basmç yükü için analitik ifade elde edilir. Detaylı parametrik analiz yapdarak, Winkler zemini, malzeme kompozisyonu, hacim indeksini ve kabuk karakteristikleri degisiminin kritik yanal basmç yüküne etkisi incelenmektedirThe buckling analysis is investigated for three layered composite cylindrical shells with simply supported edges that composed of ceramic, FGM, and metal layers subjected to uniform lateral pressure and resting on a Winkler foundation. Material properties of FG layer are varied continuously in thickness direction according to a simple power distribution. The governing equations of three layered cylindrical shells resting on elastic foundations are obtained. Applying Galerkin's method analytic solutions are obtained for the critical lateral pressure. The detailed parametric studies are carried out to study the influences of a Winkler foundation, material composition and material profile index on the critical lateral pressure

Effects of the non-homogeneity and elastic medium on the critical torsional load of the orthotropic cylindrical shell

In this study, the torsional stability problem of non-homogeneous orthotropic composite cylindrical shells in the elastic medium, using the Galerkin method was investigated. The Winkler model is used to describe the reaction of the elastic medium on the cylindrical shell. Mixed boundary conditions are considered. The effects of variations of shell parameters, non-homogeneity, orthotropy and foundation stiffness on the critical torsional load are examined

Stability analysis of FGM layered shells in the surrounding medium

In this study, the stability analysis of three-layered shells containing a functionally graded material layer in the surrounding medium and subjected to the uniform lateral pressure is investigated. The surrounding elastic medium is modeled as a Pasternak foundation. The dimensionless critical lateral pressures of three-layered functionally graded material shells with and without elastic foundations are obtained. Effects of compositional profiles and elastic foundation on the dimensionless critical lateral pressures have been studied