Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 2Citation - Scopus: 2Vibration Analysis and Optimal Design of Multiscale Hybrid Flax Fiber/ Graphene Nanoplatelets Reinforced Laminates Using Modified Differential Evolution Algorithm(Elsevier Sci Ltd, 2025) Ayakdas, Ozan; Artem, Hatice Seçil; Artem, H. Secil; Savran, Melih; Aydin, Levent; Adali, SarpOne of the relatively recent developments in composites is using different material combinations and nano-scale reinforcements such as Graphene Nanoplatelets (GPLs) to develop hybrid fiber composites. A further development is the use of natural flax fiber in composites in response to a growing demand over the past few decades for affordable, lightweight, and environmentally-friendly materials. In order to meet this growing demand, in the present study composites based on graphene nanoplatelets and flax fibers are investigated considering their weight, cost, and natural frequency implications. Furthermore, the Modified Differential Evolution (MDE) algorithm is implemented for the optimum design problems involving the stacking sequences and weight fractions of GPLs in each layer. For the optimal design problems, natural frequency is defined as the objective function with the design variables specified as the orientations of flax fibers and the weight contents of GPLs in each layer. The effective material properties are computed based on Halpin-Tsai and the rule of mixture formulations. Navier solution approach is implemented to solve the eigenvalue problems with the stiffness matrix based on the Firstorder Shear Deformation Theory (FSDT). Optimal designs based on flax fibers, optimal GPL contents, and stacking sequences lead to efficient and environmentally-friendly composite plates. Optimum multiscale hybrid nanocomposite designs include high natural frequency, light weight, and cost-effectiveness compared to conventional carbon and glass fibers reinforced equivalents.Article Citation - WoS: 16Citation - Scopus: 22Optimum Design of Fatigue-Resistant Composite Laminates Using Hybrid Algorithm(Elsevier Ltd., 2017) Deveci, Hamza Arda; Artem, Hatice SeçilIn this study, a fatigue life prediction model termed as Failure Tensor Polynomial in Fatigue (FTPF) is applied to the optimum stacking sequence design of laminated composites under various in-plane cyclic loadings to obtain maximum fatigue life. The validity of the model is investigated with an experimental correlation using the data available in the literature. The correlation study indicates the reliability of FTPF, and its applicability to different composite materials and multidirectional laminates. In the optimization, a hybrid algorithm combining genetic algorithm and generalized pattern search algorithm is used. It is found by test problems that the hybrid algorithm shows superior performance in finding global optima compared to the so far best results in the literature. After the verifications, a number of problems including different design cases are solved, and the optimum designs constituted of discrete fiber angles which give the maximum possible fatigue lives are proposed to discuss. A comparison study is also performed with selected design cases to demonstrate potential advantages of using non-conventional fiber angles in design.Article Citation - WoS: 7Citation - Scopus: 7Exact Solution and Dynamic Buckling Analysis of a Beam-Column System Having the Elliptic Type Loading(Springer Verlag, 2010) Artem, Hatice Seçil; Aydın, LeventThis paper presents a closed form solution to the dynamic stability problem of a beam-column system with hinged ends loaded by an axial periodically time-varying compressive force of an elliptic type, i.e., a 1cn 2(τ, k 2) + a 2sn2(τ, k 2) + a 3dn2(τ, k 2). The solution to the governing equation is obtained in the form of Fourier sine series. The resulting ordinary differential equation is solved analytically. Finding the exact analytical solutions to the dynamic buckling problems is difficult. However, the availability of exact solutions can provide adequate understanding for the physical characteristics of the system. In this study, the frequency-response characteristics of the system, the effects of the static load, the driving forces, and the frequency ratio on the critical buckling load are also investigated. © 2010 Shanghai University and Springer-Verlag Berlin Heidelberg.Article Citation - WoS: 5Citation - Scopus: 7Axisymmetric Crack Problem of Thick-Walled Cylinder With Loadings on Crack Surfaces(Elsevier Ltd., 2008) Aydın, Levent; Artem, Hatice SeçilThis study is concerned with the fracture of an infinite thick-walled cylinder. The inner surface of the cylinder is stress free and the outer is rigidly fixed. The cylinder having a ring-shaped crack located at the symmetry plane is subjected to distributed compressive load on its surfaces. The Hankel and Fourier transform techniques are used for the solution of the field equations. By applying the boundary conditions, the singular integral equation in terms of crack surface displacement derivative is derived. By using an appropriate quadrature formula, the integral equation is reduced to a system of linear algebraic equations. Numerical results are obtained for the stress intensity factors at the edges of the crack, surfaces of which are subjected to uniform, linear and parabolic load distributions.Conference Object Citation - WoS: 7Citation - Scopus: 9An Elastic Hollow Cylinder Under Axial Tension Containing a Crack and Two Rigid Inclusions of Ring Shape(Elsevier Ltd., 2002) Artem, Hatice Seçil; Geçit, Mehmet RuşenThis paper is concerned with the fracture of an axisymmetric hollow cylindrical bar containing rigid inclusions. The cylinder is under the action of uniformly distributed axial tension applied at infinity. The bar contains a ring-shaped crack at the symmetry plane whose surfaces are free of tractions and two ring-shaped rigid inclusions with negligible thickness symmetrically located on both sides of the crack. It is assumed that the material of the cylinder is linearly elastic and isotropic. The mixed boundary conditions of the problem lead the analysis to a system of three singular integral equations for crack surface displacement derivative and normal and shearing stress jumps on rigid inclusions. These integral equations are solved numerically and the stress intensity factors are calculated.