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- MakaleYalnız künye2024Scopus SJRQ2Analyzing of continuous and discontinuous contact problems of a functionally graded layer: theory of elasticity and finite element method
Yaylacı, Murat; Öner, Erdal; Adıyaman, Gökhan; Öztürk, Şevval; Uzun Yaylacı, Ecren; Birinci, Ahmet
Contact mechanics analysis is crucial because such problems often arise in engineering practice. When examining contact mechanics, the material property of the contacting components is a crucially significant aspect. It is more complex to solve the contact mechanics of systems that are composed of materials that do not have a homogenous structure compared to materials that have homogeneous qualities throughout. While many studies on contact problems with homogeneous materials exist, those involving non-homogeneous materials are scarce in the literature. As material technology improves fast, there will be a greater need to solve such problems. In this respect, analytical and finite element method (FEM) solutions of the continuous and discontinuous contact problems of a functionally graded (FG) layer are carried out in this article. The FG layer in the problem rests on a rigid foundation and is pressed with a rigid punch. From the solutions, the contact length, contact stress, initial separation distance, and beginning and ending points of separation were determined, and the results were compared. It has been concluded that the FEM findings are consistent with the analytical results to a satisfactory degree. This study analyzes contact problem using different approaches and accounts for the influence of body force in a contact geometry that has yet to be reported.
AtıfScopus79WoS83OpenAlex68
İncele - MakaleYalnız künye2024Scopus SJRQ1Research of the crack problem of a functionally graded layer
Yaylacı, Murat; Yaylacı, Ecren Uzun; Turan, Muhittin; Özdemir, Mehmet Emin; Öztürk, Şevval; Ay, Sevil
In this study, the two-dimensional crack problem was investigated by using the finite element method (FEM)based ANSYS package program and the artificial neural network (ANN)-based multilayer perceptron (MLP) method. For this purpose, a half-infinite functionally graded (FG) layer with a crack pressed through two rigid blocks was analyzed using FEM and ANN. Mass forces and friction were neglected in the solution. To control the validity of the crack problem model exercised, the acquired results were compared with a study in the literature. In addition, FEM and ANN results were checked using Root Mean Square Error (RMSE) and coefficient of determination (R2), and a well agreement was found. Numerical solutions were made considering different geometric parameters and material properties. The stress intensity factor (SIF) was examined for these values, and the results were presented. Consequently, it is concluded that the considered non-dimensional quantities have a noteworthy influence on the SIF. Also FEM and ANN can be logical alternative methods to time-consuming analytical solutions if used correctly.
AtıfScopus27WoS30OpenAlex6İncele - MakaleAçık Erişim2023Scopus SJRQ3A STUDY ON THE CONTACT PROBLEM OF A LAYER CONSISTING OF FUNCTIONALLY GRADED MATERIAL (FGM) IN THE PRESENCE OF BODY FORCE
Adiyaman, Gökhan; Öner, Erdal; Yaylaci, Murat; Birinci, Ahmet
One of the most important components of the early design process for layered systems is gaining a knowledge of the behavior of materials under varied contact situations. Functionally graded materials (FGMs) have grown in popularity in layered systems as a result of their numerous benefits, such as permitting the reduction of local stress concentrations and thermal stresses often experienced in traditional composites. This paper suggests an analytical approach to solving the continuous and discontinuous contact problems of a functionally graded (FG) layer subjected to a distributed load. Elasticity theory and integral transform methods provide the basis of the aforementioned analytical approach. The FG layer rests on a half-plane that is homogeneous, and there is no adhesion or bonding at the contact surface. For this problem, we assume an exponentially varying shear modulus and mass density in the FG layer. In the solution, the body force of the FG layer is considered. The problem is solved analytically by applying boundary conditions for both continuous and discontinuous contact cases. The presented results show the effects of load factor, amplitude of distributed load, inhomogeneity parameters, and interface material property mismatch on contact stress distributions, initial separation load (critical load), initial separation distance, starting and end point of separation, and separation interval.
AtıfScopus39WoS40OpenAlex30İncele - MakaleYalnız künye2021Scopus SJRQ1Investigation of continuous and discontinuous contact cases in the contact mechanics of graded materials using analytical method and FEM
Yaylacı, Murat; Adıyaman, Gökhan; Öner, Erdal; Birinci, Ahmet
The aim of this paper was to examine the continuous and discontinuous contact problems between the functionally graded (FG) layer pressed with a uniformly distributed load and homogeneous half plane using an analytical method and FEM. The FG layer is made of non-homogeneous material with an isotropic stress–strain law with exponentially varying properties. It is assumed that the contact at the FG layer-half plane interface is frictionless, and only the normal tractions can be transmitted along the contacted regions. The body force of the FG layer is considered in the study. The FG layer was positioned on the homogeneous half plane without any bonds. Thus, if the external load was smaller than a certain critical value, the contact between the FG layer and half plane would be continuous. However, when the external load exceeded the critical value, there was a separation between the FG layer and half plane on the finite region, as discontinuous contact. Therefore, there have been some steps taken in this study. Firstly, an analytical solution for continuous and discontinuous contact cases of the problem has been realized using the theory of elasticity and Fourier integral transform techniques. Then, the problem modeled and two-dimensional analysis was carried out by using ANSYS package program based on FEM. Numerical results for initial separation distance and contact stress distributions between the FG layer and homogeneous half plane for continuous contact case; the start and end points of separation and contact stress distributions between the FG layer and homogeneous half plane for discontinuous contact case were provided for various dimensionless quantities including material inhomogeneity, distributed load width, the shear module ratio and load factor for both methods. The results obtained using FEM were compared with the results found using analytical formulation. It was found that the results obtained from analytical formulation were in perfect agreement with the FEM study.
AtıfScopus78WoS78OpenAlex21İncele - MakaleYalnız künye2020Scopus SJRQ2Examination of analytical and finite element solutions regarding contact of a functionally graded layer
Yaylacı, Murat; Adıyaman, Gökhan; Öner, Erdal; Birinci, Ahmet
In this study, the continuous and discontinuous contact problems of functionally graded (FG) layer resting on a rigid foundation were considered. The top of the FG layer was loaded by a distributed load. It was assumed that the shear modulus and the density of the layer varied according to exponential functions along the depth whereas the the Poisson ratio remained constant. The problem first was solved analytically and the results were verified with the ones obtained from finite element (FE) solution. In analytical solution, the stress and displacement components for FG layer were obtained by the help of Fourier integral transform. Critical load expression and integral equation for continuous and discontinuous contact, respectively, using corresponding boundary conditions in each case. The finite element solution of the problem was carried out using ANSYS software program. In continuous contact case, initial separation distance and contact stresses along the contact surface between the FG layer and the rigid foundation were examined. Separation distances and contact stresses were obtained in case of discontinuous contact. The effect of material properties and loading were investigated using both analytical and FE solutions. It was shown that obtained results were compatible with each other.
AtıfScopus71WoS72OpenAlex22İncele - MakaleAçık Erişim2020Scopus SJRQ2Investigation of the solution for discontinuous contact problem between a functionally graded (FG) layer and homogeneous half-space
Öner, Erdal; Birinci, Ahmet
In this study, the discontinuous contact problem between a functionally graded (FG) layer, which is loaded symmetrically with point load P through a rigid block, and a homogeneous half-space was solved using the theory of elasticity and integral transform techniques. The shear modulus and density of the layer addressed in the problem vary with an exponential function along with its height. The half-space is homogeneous, and no binder exists on the contact surface containing the FG layer. In the solution, the body force of the FG layer was considered, whereas that of the homogeneous half-space was neglected. The Poisson’s ratios of both the FG layer and homogeneous half-space were assumed to remain constant. Additionally, all the surfaces addressed in the problem were assumed to be frictionless. Using the theory of elasticity and integral transform techniques, the discontinuous contact problem was reduced to two integral equations, wherein the contact stress under the rigid block and the slope of the separation, which occurred at the interface of the FG layer and homogeneous half-space, are unknown. These integral equations were solved numerically for the flat condition of the rigid block profile using the Gauss–Chebyshev integration formula. Consequently, the stress distributions, start–end points of the separation region, and separation displacements between the FG layer and homogeneous half-space were obtained for various dimensionless quantities.
AtıfScopus24WoS25OpenAlex23İncele - MakaleYalnız künye2017Scopus SJRQ3Continuous contact problem of a functionally graded layer resting on an elastic half-plane
Öner, E.; Adiyaman, G.; Birinci, A.
In this study, the continuous contact problem of a functionally graded layer resting on an elastic half-plane and loaded by a rigid rectangular stamp is examined. The problem is solved assuming that the functionally graded (FG) layer is isotropic and the shear modulus and mass density vary exponentially throughout the layer's thickness. However, the body force of the elastic half-plane is neglected. In addition, it is assumed that all surfaces are frictionless and only compressive stress is transferred along the contact surfaces. The mathematical problem is reduced to a singular integral equation in which the contact stress under the rigid stamp is unknown using the Fourier integral transform and boundary conditions related to the problem. This singular integral equation is solved numerically using the Gauss-Chebyshev integration formula. The dimensionless contact stress under the rigid stamp, the initial separation loads and the initial separation distances between the FG layer and the elastic half-plane are obtained for various dimensionless quantities.
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