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: 40Citation - Scopus: 37Investigation of Interlayer Hybridization Effect on Burst Pressure Performance of Composite Overwrapped Pressure Vessels With Load-Sharing Metallic Liner(SAGE Publications, 2020) Kangal, Serkan; Kartav, Osman; Tanoğlu, Metin; Aktaş, Engin; Artem, Hatice SeçilIn this study, multi-layered composite overwrapped pressure vessels for high-pressure gaseous storage were designed, modeled by finite element method and manufactured by filament winding technique. 34CrMo4 steel was selected as a load-sharing metallic liner. Glass and carbon filaments were overwrapped on the liner with a winding angle of [+/- 11 degrees/90 degrees(2)](3) to obtain fully overwrapped composite reinforced vessel with non-identical front and back dome endings. The vessels were loaded with increasing internal pressure up to the burst pressure level. The mechanical performances of pressure vessels, (i) fully overwrapped with glass fibers and (ii) with additional two carbon hoop layers on the cylindrical section, were investigated by both experimental and numerical approaches. In numerical approaches, finite element analysis was performed featuring a simple progressive damage model available in ANSYS software package for the composite section. The metal liner was modeled as elastic-plastic material. The results reveal that the finite element model provides a good correlation between experimental and numerical strain results for the vessels, together with the indication of the positive effect on radial deformation of the COPVs due to the composite interlayer hybridization. The constructed model was also able to predict experimental burst pressures within a range of 8%. However, the experimental and finite element analysis results showed that hybridization of hoop layers did not have any significant impact on the burst pressure performance of the vessels. This finding was attributed to the change of load-sharing capacity of composite layers due to the stiffness difference of carbon and glass fibers.Book Part Citation - WoS: 3Citation - Scopus: 4Design and Optimization of Fiber Composites(Elsevier, 2017) Aydın, Levent; Artem, Hatice SeçilIn engineering, design, and optimization processes are very important issues to establish sustainable engineering systems. Compared to isotropic materials, it is necessary to deal with more complicated mathematical models that address the material anisotropy for fiber-reinforced composites. Due to the unique characteristics of fiber-reinforced composite materials such as different directional properties, interlaminar stresses, less notch sensitivity, and having positive and negative coefficients of thermal expansion, they require more material constants for characterization of the hygrothermomechanical responses. Therefore, the design process of composites for the effort required or the benefit desired has to be systematic, which includes innovative approaches to synthesize alternative solutions. In this regard, the main goal of all such attempt is relevant to reach minimizing the effort required or to maximize the desired benefit.Book Part Citation - WoS: 4Citation - Scopus: 4Mechanics of Fiber Composites(Elsevier, 2017) Aydın, Levent; Artem, Hatice Seçil; Öterkuş, Erkan; Gündoğdu, Ömer; Akbulut, HamitThe objective of this chapter is to emphasize the context in which the mechanics of fiber composites is examined. Constitutive equations describing the stress-strain relations, micromechanics and acromechanics approaches for mechanical analysis are reviewed. Since interfacial mechanics of composites is of primary importance in discussing the material behavior, this concept is also presented with its constitutive and governing equations. Finally, at the end of the chapter, strength failure theories for orthotropic materials and dynamic behavior of composites are discussed.Article Citation - WoS: 9Citation - Scopus: 10On the Estimation and Optimization Capabilities of the Fatigue Life Prediction Models in Composite Laminates(SAGE Publications, 2018) Deveci, Hamza Arda; Artem, Hatice SeçilIn this study, the estimation and optimization capabilities of the multiaxial fatigue life prediction models, namely, Failure Tensor Polynomial in Fatigue, Fawaz-Ellyin, Sims-Brogdon and Shokrieh-Taheri are investigated comparatively. Fatigue life predictions are obtained for multidirectional graphite/epoxy, glass/epoxy, carbon/epoxy and carbon/PEEK composite laminate data taken from the literature. The prediction study shows that the models can predict the fatigue behavior of the multidirectional laminates at different degrees of proximity. In the optimization, a hybrid algorithm combining particle swarm algorithm and generalized pattern search algorithm is used to search the optimum stacking sequence designs of the laminated composites for maximum fatigue life. The hybrid algorithm shows superior performance in terms of computational time and finding improved global optima compared to the best results presented in the literature. After the capability of the models and the reliability of the algorithm are revealed, several lay-up design problems involving different cyclic loading scenarios are solved. The results indicate that the reliability of the optimization may considerably change according to the used model even if the model may yield reasonable prediction results.Article Citation - WoS: 13Citation - Scopus: 17Design of Dimensionally Stable Composites Using Efficient Global Optimization Method(SAGE Publications Inc., 2019) Aydın, Levent; Aydın, Olgun; Artem, Hatice Seçil; Mert, AliDimensionally stable material design is an important issue for space structures such as space laser communication systems, telescopes, and satellites. Suitably designed composite materials for this purpose can meet the functional and structural requirements. In this paper, it is aimed to design the dimensionally stable laminated composites by using efficient global optimization method. For this purpose, the composite plate optimization problems have been solved for high stiffness and low coefficients of thermal and moisture expansion. Some of the results based on efficient global optimization solution have been verified by genetic algorithm, simulated annealing, and generalized pattern search solutions from the previous studies. The proposed optimization algorithm is also validated experimentally. After completing the design and optimization process, failure analysis of the optimized composites has been performed based on Tsai-Hill, Tsai-Wu, Hoffman, and Hashin-Rotem criteria.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: 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.