Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
5 results
Search Results
Article Citation - WoS: 32Citation - Scopus: 38Buckling Optimization of Composite Laminates Using a Hybrid Algorithm Under Puck Failure Criterion Constraint(SAGE Publications Inc., 2016) Deveci, Hamza Arda; Aydın, Levent; Artem, Hatice SeçilIn this study, an optimization procedure is proposed to find the optimum stacking sequence designs of laminated composite plates in different fiber angle domains for maximum buckling resistance. A hybrid algorithm combining genetic algorithm and trust region reflective algorithm is used in the optimization to obtain higher performance and improve the quality of solutions. As a novelty, Puck fiber and inter-fiber failure criteria are directly implemented to the optimization problems as nonlinear function constraints, which have allowed more consistent and feasible results. The performance of the hybrid algorithm is demonstrated by comparing with the individual performances of genetic and trust region reflective algorithms via test problems from the literature. Also, a study is performed to exhibit the effectiveness of the selected failure criterion as constraint among the other common criteria. The proposed procedure is used to solve many problems including various design considerations. The results indicate that reliable stacking sequence designs can be achieved in specific configurations even for the composite plates subjected to superior buckling loads when Puck physically based (3D) failure theory is considered as a first ply failure constraint in the buckling optimization.Article Citation - WoS: 19Citation - Scopus: 19Comparison of Stochastic Search Optimization Algorithms for the Laminated Composites Under Mechanical and Hygrothermal Loadings(SAGE Publications Inc., 2011) Aydın, Levent; Artem, Hatice SeçilThe aim of the present study is to design the stacking sequence of the laminated composites that have low coefficient of thermal expansion and high elastic moduli. In design process, multi-objective genetic algorithm optimization of the carbon fiber laminated composite plates is verified by single objective optimization approach using three different stochastic optimization methods: genetic algorithm, generalized pattern search, and simulated annealing. However, both the multi- and single-objective approaches to laminate optimization have been used by considerably few authors. Simplified micromechanics equations, classical lamination theory, and MATLAB Symbolic Math toolbox are used to obtain the fitness functions of the optimization problems. Stress distributions of the optimized composites are presented through the thickness of the laminates subjected to mechanical, thermal, and hygral loadings.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.Conference Object Citation - WoS: 5Citation - Scopus: 6Multiobjective Genetic Algorithm Optimization of the Composite Laminates as a Satellite Structure Material for Coefficient of Thermal Expansion and Elastic Modulus(Institute of Electrical and Electronics Engineers Inc., 2009) Aydın, Levent; Artem, Hatice SeçilThis study considers multi-objective optimal design of the fiber reinforced symmetric-balanced laminated composites using genetic algorithms. MATLAB Genetic Algorithm and Direct Search Toolbox is used to obtain Pareto-optimal design for three different model problems. The objectives of the problems are to maximize the Young's moduli and minimize the coefficient of thermal expansion (CTE) simultaneously for 8 and 16 layered carbon/epoxy composites. Simplified micromechanics equations and classical lamination theory are used in order to obtain the fitness functions of the problems. Stress and strain distributions are presented through the thickness of the laminates for the optimized problems under mechanical and thermal loadings.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.