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Постійне посилання на розділhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/35393
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Документ A New Numerical Procedure for Determination of Effective Elastic Constants in Unidirectional Composite Plates(IAU, Arak Branch, 2016) Darya zadeh, S.; Lvov, G. I.; Tajdari, M.In this paper a composite plate with similar unidirectional fibers is considered. Assuming orthotropic structure, theory of elasticity is used for investigating the stress concentration. Also, complex variable functions are utilized for solving the plane stress problems. Then the effective characteristics of this plate are studied numerically by using ANSYS software. In this research a volume element of fibers in square array is considered. In order to investigate the numerical finite element modeling, the modeling of a quarter unit cell is considered. For determining the elasticity coefficients, stress analysis is performed for considered volume with noting to boundary conditions. Effective elasticity and mechanical properties of composite which polymer epoxy is considered as its matrix, are determined theoretically and also by the proposed method in this paper with finite element method. Finally, the variations of mechanical properties with respect to fiber-volume fraction are studied.Документ Stress analysis in an infinite hydroxyapatite / titanium plate with a pressurized circular hole(Удмуртский государственный университет, 2015) Darya zadeh, S.; Lvov, G. I.The aim of the present study is to compute the macro- and microstress concentration in a reinforced biomaterial composite plate with a circular hole with respect to the volume ratio of the component materials in the composite. The contour of the circular hole and its dependency on the structure of a plate were calculated in order to study the behaviors of macro- and microstresses. In this paper, the stress around a circular hole was calculated for an orthotropic unidirectionally ber-reinforced plate with respect to the volume ratio of the component materials in the composite. Stress distribution using a theoretical method and the nite elements method was calculated. The boundary conditions applied on the contour of a circular hole are uniform normal pressure. In this present study, we use a new numerical method of determining microstresses for composite plates with a circular hole, on the boundary of which there is a uniform normal pressure. The results demonstrate the macro- and microstresses calculated for two di erent structures and the behavior of an orthotropic plate with a circular hole. The ANSYS package and the nite-element representative plate model were used in this study.Документ A two-level method for calculation of microstress on reinforced plates with circular hole in case of extension normal to principal direction(Пермский национальный исследовательский политехнический университет, 2015) Darya zadeh, S.; Lvov, G. I.The stress concentration must often be examined at two levels while analyzing the stress condition of composite materials. The macroconcentration depends on the presence of holes, notches and other local areas of a construction. Typical dimensions of macroconcentration distribution areas are of the order of 0,01–0,1 m. Macroconcentration analysis is performed using the models of homogeneous material. Microstress concentration occurs in structurally inhomogeneous composites due to the structural heterogeneity of the composite. The sizes of concentration areas in regular structures are defined by the sizes of periodically recurring areas. In fibrous composites, such areas have the size of approximately 0,0001 m or less. This makes it necessary to use a two-level approach for the analysis of the stress concentration in the construction of composite materials. The aim of the present study was to compute the stress concentration in unidirectional reinforced composite plate with circular hole with respect to the volume ratio of the component materials in composite. The contour of the circular hole and its dependency on the structure of plates was calculated in order to study the behaviors of macro- and microstresses. The boundary conditions at a large distance from the hole are pressure, uniformly distributed on the plate. Also this problem is analyzed with the finite element method by package ANSYS. Macroconcentration is defined based on the solution of the plane problem of elasticity theory of the orthotropic material by the virtue of functions of a complex variable. The finite element method was used to investigate the stress distribution at microlevel. Boundary conditions that model the state of the specified twodimensional representative cell in the composite structure were established. The results demonstrated the macro- and microstresses and behavior of the orthotropic plate with a circular hole calculated for two different structures.Документ The calculation of effective elastic constants in a composite with 3d orthogonal nonwoven fibers(Томский государственный университет, 2015) Darya zadeh, S.; Lvov, G. I.The paper is devoted to the research of the effective characteristics of 3D orthogonal nonwoven fibers composites. The results were received via ANSYS software package. In this research a volume element of fibers in cubic unit cell is considered. The effective elastic properties of fiber reinforced composite have been defined by the numerical stress analysis of the unit cell.Документ A new numerical method for determination of effective elastic constants in a composite with 3D orthogonal nonwoven fibers(НТУ "ХПИ", 2015) Darya zadeh, S.; Lvov, G. I.Документ A New Numerical Method for Calculation of Micro- Stress on Unidirectionally Reinforced Plates with Circular Hole In Case of Extension to a Principal Direction(ORIC Publications, 2014) Darya zadeh, S.; Lvov, G. I.; Daryazadeh, P.The aim of the present study was to compute the stress concentration in reinforced composite plate with circular hole with respect to the volume ratio of the component materials in composite. The contour of the circular hole and its dependency on the structure of plates were calculated in order to study the behaviors of macro and micro-stresses. The boundary conditions at a large distance from the hole are pressure, uniformly distributed on the plate. Also this problem is analyzed with the finite element method by package ANSYS. The results demonstrated the macro and micro stress and behavior of the orthotropic plate with a circular hole calculated for two different structures.Документ A new numerical method for determination of effective elastic constants in a composite with cross-ply fibers(НТУ "ХПИ", 2014) Darya zadeh, S.; Lvov, G. I.; Kiahosseini, Seyed RahimIn this paper a composite material with similar cross-ply fibers is considered. Assuming orthotropic structure, theory of elasticity is used for investigating the stress concentration. The effective characteristicsof this composite are studied numerically by using ANSYS software. In this research a volume element of fibers in square array in the coordinate x, y, z and the generalized stress state is considered. In order to investigate the numerical finite element modeling, the modeling of a quarter unit cell is considered. For determining the elasticity coefficients, stress analysis is performed for considered volume with noting to boundary conditions. Effective elasticity and mechanical properties of composite which polymer epoxy is considered as its matrix, are determined theoretically and also by the proposed method in this paper with finite element method. Numerical experiments modeled four cases of uniaxial tension in the directions x, z and shear in the planes xy, yz. Finally, the variations of mechanical properties with respect to fiber-volume fraction are studied. Numerical results are compared with approximate estimates method proposed.