Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleYalnız künye2020Analytical and finite element solutions of continuous contact problem in functionally graded layer
Kaya, Yusuf; Polat, Alper; Özşahin, Talat Şükrü
In this study, we solve the continuous contact problem of two layers with different material properties, loaded with two rigid flat blocks and resting on a rigid plane, by analytical and finite element methods. All surfaces are assumed to be frictionless. The upper layer is the functionally graded layer (FG), the height h1, the underlying layer is homogeneous, and the height is h2. It is assumed that the FG layer is isotropic and that the shear modulus and density change exponentially. The FG layer is loaded by means of two rigid flat blocks whose external loads are Q and P (per unit thickness in z direction). In the analytical solution of the problem, stress and displacement expressions are substituted in the boundary conditions and the problem is demoted to singular integral equations where the contact stresses are the unknown functions. These singular integral equations are solved numerically using the Gauss–Chebyshev integration formulas. Two-dimensional finite element analysis of the problem is performed using the ANSYS package program. The analyses are performed for different shear modulus ratios (μ2/μ-h1), distances between the blocks ((c − b)/h1) and inhomogeneity parameters (βh1). The contact stresses under the blocks, the normal stresses (σy) between interfaces of the FG layer and the homogeneous layer and between the homogeneous layer and rigid plane are also measured. In addition, the initial separation load and the initial separation distances (χcr, λcr) of the FG layer and homogeneous layer are determined. The results are presented comparatively as graphs and tables.
- MakaleYalnız künye2018Analysis of Frictionless Contact Problem for A Weighted Layer on An Elastic Half Plane Using FEM
Polat, Alper; Kaya, Yusuf; Özşahin, Talat Şükrü
In this study, a comparative analysis of the continuous contact problem of a homogeneous layer loaded by two rigid flat blocks and resting on elastic half plane is investigated using the finite element method (FEM). The results obtained from the elasticity solution are compared with FEM solutions. Also in this problem, it is assumed that the all surfaces are frictionless. Two dimensional finite element analysis of the problem is carried out using ANSYS Mechanical APDL. The analyzes are performed for different loading conditions of Q and P loads. Initial separation load and initial separation points (xcr, λcr) and normal stresses (σy) between the homogenous layer and the elastic half plane are determined. The obtained results are shown in graphs and tables.
- MakaleYalnız künye2018Analytical solution to continuous contact problem for a functionally graded layer loaded through two dissimilar rigid punches
Polat, Alper; Kaya, Yusuf; Özşahin, Talat Şükrü
A continuous contact problem of functionally graded layer resting on an elastic semi-infinite plane, which is loaded with through two different blocks is addressed in this study. The elasticity theory and integral transformation techniques are used in solution of the problem. The problem is reduced to a system of singular integral equations, and solved numerically by the aid of appropriate Gauss–Chebyshev integration formula. It is assumed that the elastic semi-infinite homogeneous plane is isotropic and all surfaces are frictionless and continuous. The shear modulus and the mass density of the FG layer vary exponentially along the thickness direction.
- MakaleYalnız künye2011Modeling and forecasting of Turkey's energy consumption using socio-economic and demographic variables
Kankal, Murat; Akpinar, Adem; Kömürcü, Murat Ihsan; Özşahin, Talat Şükrü
This study deals with the modeling of the energy consumption in Turkey in order to forecast future projections based on socio-economic and demographic variables (gross domestic product-GDP, population, import and export amounts, and employment) using artificial neural network (ANN) and regression analyses. For this purpose, four diverse models including different indicators were used in the analyses. As the result of the analyses, this research proposes Model 2 as a suitable ANN model (having four independent variables being GDP, population, the amount of import and export) to efficiently estimate the energy consumption for Turkey. The proposed model predicted the energy consumption better than the regression models and the other three ANN models. Thus, the future energy consumption of Turkey is calculated by means of this model under different scenarios. The predicted forecast results by ANN were compared with the official forecasts. Finally, it was concluded that all the scenarios that were analyzed gave lower estimates of the energy consumption than the MENR projections and these scenarios also showed that the future energy consumption of Turkey would vary between 117.0 and 175.4. Mtoe in 2014.