Tamamlayıcı Fonksiyonlar Metodu İle Üniform Olmayan Kesite Sahip Çubuğun Zorlanmış Titreşim Analizi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Sürekli sistem olarak modellenen eksenel yüklenmiş değişken kesitli bir çubuğun elastik davranış problemi analiz edilmiştir. Bu problemi modelleyen diferansiyel denklemlere Laplace dönüşümü uygulanarak zamandan bağımsız sınır değer problemi eksenel koordinatlarda elde edilmiş daha sonra bu problem tamamlayıcı fonksiyonlar metodu (TFM) tarafından çözülmüştür. Sayısal olarak çözülen denklemler Durbin’in sayısal ters dönüşümünü yardımıyla zaman uzayına dönüştürülmüştür. Her bir yükleme tipi ve inhomojenlik parametresi için elde edilen sayısal sonuçlar, analitik sonuçlar ve ANSYS sonuçları ile karşılaştırılmıştır. Bu birleşik yöntem, iyi yapılandırılmış, basit ve etkili bir yöntemdir.The axial vibration problem formulation and solution of a nonuniform rod modeled as a continuous system were analyzed. By applying Laplace transformation to the differential equations that model to this problem, time independent boundary value problems were obtained in the axial coordinates, then this problem is solved by the complementary functions method. The equations solved numerically is converted into time space with the help of Durbin's numerical inverse transformation. The numerical results that obtained for each load type and inhomogeneity parameter were compared with analytical and ANSYS results in the literature. This unified method is well-structured, simple and efficient

A Spectral Solenoidal-Galerkin Method for Rotating Thermal Convection between Rigid Plates

The problem of thermal convection between rotating rigid plates under the influence of gravity is treated numerically. The approach uses solenoidal basis functions and their duals which are divergence free. The representation in terms of the solenoidal bases provides ease in the implementation by a reduction in the number of dependent variables and equations. A Galerkin procedure onto the dual solenoidal bases is utilized in order to reduce the governing system of partial differential equations to a system of ordinary differential equations for subsequent parametric study. The Galerkin procedure results in the elimination of the pressure and is facilitated by the use of Fourier-Legendre spectral representation. Numerical experiments on the linear stability of rotating thermal convection and nonlinear simulations are performed and satisfactorily compared with the literature

Manyetik bir alan etkisinde ısıl konveksiyon hareketinin solenoidal baz kullanımı ile sayısal benzetimi.

The effect of an imposed magnetic field on the thermal convection between rigid plates heated from below under the influence of gravity is numerically simulated in a computational domain with periodic horizontal extent. The numerical technique is based on solenoidal basis functions satisfying the boundary conditions for both velocity and induced magnetic field. The expansion bases for the thermal field are also constructed to satisfy the boundary conditions. The governing partial differential equations are reduced to a system of ordinary differential equations governing the time evolution of the expansion coefficients under Galerkin projection onto the subspace spanned by the dual bases. In the process, the pressure term in the momentum equation is eliminated. The system validated in the linear regime is then used for some numerical experiments in the nonlinear regime.Ph.D. - Doctoral Progra

Thermomechanical responses of functionally graded cylinders

In this study, thermal and mechanical stresses in hollow thick-walled functionally graded (FG) cylinders is presented under the convection boundary condition. The convective external condition and constant internal temperature in hollow cylinders are investigated. Inhomogeneous material properties produce irregular and two-point linear boundary value problems that are solved numerically by the pseudospectral Chebyshev method. The displacement and thermal stress distributions are examined for two different material couples under particular boundary conditions that are similar to their real engineering applications.Results have demonstrated that the pseudospectral Chebyshev method has low computation costs, high accuracy and ease of implementation and can be easily customized to such engineering problems