Papers by Marina Cetkovic
In this paper Generalized Layer Wise Plate Theory of Reddy (GLPT) is used to formulate an isopara... more In this paper Generalized Layer Wise Plate Theory of Reddy (GLPT) is used to formulate an isoparametric finite element model for free vibration of laminated composite plates. With the assumed displacement field, linear strain displacement relations and linear elastic orthotropic material properties for each lamina, virtual work statement is utilized in order to formulate isoparametric finite element model. The original MATLAB computer program is coded for finite element solution. Some new results using GLPT finite element model for soft core sandwich plate is presented, which may be used as the guideline for their optimal design in the laboratory
In this paper the geometrically nonlinear laminated finite element model is developed using the p... more In this paper the geometrically nonlinear laminated finite element model is developed using the principle of virtual displacements (PVD). The 3D elasticity equations are reduced to 2D problem using kinematical assumptions based on assumed layer wise displacement field of Reddy. With the assumed displacement field, nonlinear Green-Lagrange small strain large displacements relations and linear orthotropic material properties for each lamina, the PVD is used to obtain the weak form of the problem. The weak form or nonlinear integral equilibrium equations are discretized using isoparametric finite element approximation. The nonlinear incremental algebric equilibrium equations are solved using the direct iteration procedure. The original MATLAB computer program is coded for finite element solution and is used to investigate the geometrical nonlinear effects on displacement and stress field of thin and thick, isotropic, orthotropic and anisotropic laminated composite plates with various b...
In this paper the infl uence of different boundary conditions on geometrically nonlinear response... more In this paper the infl uence of different boundary conditions on geometrically nonlinear response of laminated composite plates is analyzed. Mathematical model, based on layer-wise displacement fi eld of Reddy [1], is formulated using the von Karman, small strain large defl ection theory. The principle if virtual displacements (PVD) is used to obtain the weak form of the problem. The weak form is discretized utilizing isoparametric fi nite element approximation. The originally coded MAT-LAB program is used to investigate the infl uence of different boundary conditions on geometrically nonlinear response of laminate composite plates. The accuracy of the numerical model is verifi ed by comparison with the available results from the literature.
In this paper Generalized Layer Wise Plate Theory of Reddy (GLPT) is used to formulate an isopara... more In this paper Generalized Layer Wise Plate Theory of Reddy (GLPT) is used to formulate an isoparametric finite element model for free vibrations of isotropic, orthotropic and laminated composite plates. With the assumed displacement field, linear strain displacement relations and linear elastic orthotropic material properties for each lamina, governing differential equations of motion are derived using Hamilton‘s principle. Virtual work statement is then utilized to formulate isoparametric finite element model. The original MATLAB computer program is coded for finite element solution. The parametric effects of plate aspect ratio a b / , side-tothickness ratio h a / , degree of orthotropy 2 1 / E E and boundary conditions on free vibration response of isotropic, orthotropic and anisotropic plates are analyzed. The accuracy of the present formulation is demonstrated through a number of examples and by comparison with results available from the literature.
Facta universitatis - series: Architecture and Civil Engineering, 2005
This paper deals with closed-form solution for static analysis of simply supported composite plat... more This paper deals with closed-form solution for static analysis of simply supported composite plate, based on generalized laminate plate theory (GLPT). The mathematical model assumes piece-wise linear variation of in-plane displacement components and a constant transverse displacement through the thickness. It also include discrete transverse shear effect into the assumed displacement field, thus providing accurate prediction of transverse shear stresses. Namely, transverse stresses satisfy Hook's law, 3D equilibrium equations and traction free boundary conditions. With assumed displacement field, linear strain-displacement relation, and constitutive equations of the lamina, equilibrium equations are derived using principle of virtual displacements. Navier-type closed form solution of GLPT, is derived for simply supported plate, made of orthotropic laminae, loaded by harmonic and uniform distribution of transverse pressure. Results are compared with 3D elasticity solutions and excellent agreement is found.
Istra?ivanja i projektovanja za privredu, 2012
In this paper the infl uence of different boundary conditions on geometrically nonlinear response... more In this paper the infl uence of different boundary conditions on geometrically nonlinear response of laminated composite plates is analyzed. Mathematical model, based on layer-wise displacement fi eld of Reddy [1], is formulated using the von Karman, small strain large defl ection theory. The principle if virtual displacements (PVD) is used to obtain the weak form of the problem. The weak form is discretized utilizing isoparametric fi nite element approximation. The originally coded MAT-LAB program is used to investigate the infl uence of different boundary conditions on geometrically nonlinear response of laminate composite plates. The accuracy of the numerical model is verifi ed by comparison with the available results from the literature.
In this paper Generalized Layer Wise Plate Theory of Reddy (GLPT) is used to formulate an isopara... more In this paper Generalized Layer Wise Plate Theory of Reddy (GLPT) is used to formulate an isoparametric finite element model for free vibrations of isotropic, orthotropic and laminated composite plates. With the assumed displacement field, linear strain displacement relations and linear elastic orthotropic material properties for each lamina, governing differential equations of motion are derived using Hamilton‘s principle. Virtual work statement is then utilized to formulate isoparametric finite element model. The original MATLAB computer program is coded for finite element solution. The parametric effects of plate aspect ratio b / a , side-tothickness ratio a / h , degree of orthotropy 1 2 E / E and boundary conditions on free vibration response of isotropic, orthotropic and anisotropic plates are analyzed. The accuracy of the present formulation is demonstrated through a number of examples and by comparison with results available from the literature.U ovom radu primenom Opšte lam...
Use of 4-substituted-quinazoline derivatives for producing therapeutic agents
Although the global higher-order shear deformation theories may predict the gross responses of th... more Although the global higher-order shear deformation theories may predict the gross responses of the sandwich plates sufficiently accurate, their results may show considerable errors in predicting the local effects. Layerwise and mixed layerwise theories are computationally expensive and generally, the interlaminar transverse stresses continuity conditions are not enforced in the former category of theories. Majority of the available zigzag and global–local theories suffer from the point that the transverse normal stress continuity that influences the transverse deformation significantly, especially in sandwich plates with soft-cores, is not satisfied at the layer interfaces. In the present paper, a generalized global–local theory that guarantees the continuity condition of all of the displacement and transverse stress components and considers the transverse flexibility under thermo-mechanical loads is introduced. One of the advantages of the present theory is that the number of unknown parameters is independent of the number of the layers. Furthermore, all stress components are considered in the formulations. Therefore, in contrast to the available works, the theory may be used for sandwich plates with stiff or soft cores. In contrast to the available global–local formulations, the present formulation is developed in a compact matrix form that makes it more desirable for computerized solutions. The present theory may be considered as a generalized layerwise theory with an optimized computational time. Compatible quadrilateral Hermitian elements are employed to further enhance the accuracy of the results. Validity, advantages, and efficiency of the present theory are investigated for different local and global behaviors of the layered composite and sandwich plates. Comparison of the present results with those of the three-dimensional theory of elasticity and the available plate theories confirms the efficiency and accuracy of the proposed theory. Results reveal that the global theories (e.g. the higher-order shear deformation theories) may encounter serious accuracy problems even in predicting the gross responses of the sandwich plates.
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Papers by Marina Cetkovic