Yazar "Fantuzzi, Nicholas" seçeneğine göre listele

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    Analytical Solution of Stability Problem of Nanocomposite Cylindrical Shells under Combined Loadings in Thermal Environments
    (MDPI, 2023) Avey, Mahmure; Fantuzzi, Nicholas; Sofiyev, Abdullah H.
    The mathematical modeling of the stability problem of nanocomposite cylindrical shells is one of the applications of partial differential equations (PDEs). In this study, the stability behavior of inhomogeneous nanocomposite cylindrical shells (INH-NCCSs), under combined axial compression and hydrostatic pressure in the thermal environment, is investigated by means of the first-order shear deformation theory (FSDT). The nanocomposite material is modeled as homogeneous and heterogeneous and is based on a carbon nanotube (CNT)-reinforced polymer with the linear variation of the mechanical properties throughout the thickness. In the heterogeneous case, the mechanical properties are modeled as the linear function of the thickness coordinate. The basic equations are derived as partial differential equations and solved in a closed form, using the Galerkin procedure, to determine the critical combined loads for the selected structure in thermal environments. To test the reliability of the proposed formulation, comparisons with the results obtained by finite element and numerical methods in the literature are accompanied by a systematic study aimed at testing the sensitivity of the design response to the loading parameters, CNT models, and thermal environment.
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    Buckling Behavior of Nanocomposite Plates with Functionally Graded Properties under Compressive Loads in Elastic and Thermal Environments
    (Shahid Chamran University of Ahvaz, 2023) Ipek, Cengiz; Sofiyev, Abdullah H.; Fantuzzi, Nicholas; Efendiyeva, Sadige P.
    The buckling behavior of functionally graded carbon nanotube (FG-CNT) reinforced polymer-based moderately-thick plates subjected to in-plane biaxial compressive loads in elastic and thermal environments in the framework of first-order shear deformation plate theory (FSDPT) is investigated. First, the temperature-dependent properties of CNTs and nanocomposites are defined and their constitutive relations are established, then the stability and strain compatibility equations in elastic media are derived in the framework of the FSDPT. Then, by applying the Galerkin method to the basic equations, a closed-form solution is obtained for the critical biaxial compressive loads. The specific numerical analyzes and interpretations are made for various plate sizes and CNT patterns on the Winkler elastic foundation and in thermal environments within FSDPT and classical plate theory (CPT).
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    Buckling behavior of sandwich cylindrical shells covered by functionally graded coatings with clamped boundary conditions under hydrostatic pressure
    (MDPI, 2022) Sofiyev, Abdullah H.; Fantuzzi, Nicholas; Ipek, Cengiz; Tekin, Gülçin
    The buckling behavior of sandwich shells with functionally graded (FG) coatings operating under different external pressures was generally investigated under simply supported boundary conditions. Since it is very difficult to determine the approximation functions satisfying clamped boundary conditions and to solve the basic equations analytically within the framework of first order shear deformation theory (FOST), the number of publications on this subject is very limited. An analytical solution to the buckling problem of FG-coated cylindrical shells under clamped boundary conditions subjected to uniform hydrostatic pressure within the FOST framework is presented for the first time. By mathematical modeling of the FG coatings, the constitutive relations and basic equations of sandwich cylindrical shells within the FOST framework are obtained. Analytical solutions of the basic equations in the framework of the Donnell shell theory, obtained using the Galerkin method, is carried out using new approximation functions that satisfy clamped boundary conditions. Finally, the influences of FG models and volume fractions on the hydrostatic buckling pressure within the FOST and classical shell theory (CT) frameworks are investigated in detail.
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    On the solution of thermal buckling problem of moderately thick laminated conical shells containing carbon nanotube originating layers
    (MDPI, 2022) Avey, Mahmure; Fantuzzi, Nicholas; Sofiyev, Abdullah
    This study presents the solution for the thermal buckling problem of moderately thick laminated conical shells consisting of carbon nanotube (CNT) originating layers. It is assumed that the laminated truncated-conical shell is subjected to uniform temperature rise. The Donnell-type shell theory is used to derive the governing equations, and the Galerkin method is used to find the expression for the buckling temperature in the framework of shear deformation theories (STs). Different transverse shear stress functions, such as the parabolic transverse shear stress (Par-TSS), cosine-hyperbolic shear stress (Cos-Hyp-TSS), and uniform shear stress (U-TSS) functions are used in the analysis part. After validation of the formulation with respect to the existing literature, several parametric studies are carried out to investigate the influences of CNT patterns, number and arrangement of the layers on the uniform buckling temperature (UBT) using various transverse shear stress functions, and classical shell theory (CT).
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    Stability Analysis of Shear Deformable Inhomogeneous Nanocomposite Cylindrical Shells under Hydrostatic Pressure in Thermal Environment
    (Multidisciplinary Digital Publishing Institute (MDPI), 2023) Sofiyev, Abdullah H.; Fantuzzi, Nicholas
    In this study, the stability of inhomogeneous nanocomposite cylindrical shells (INCCSs) under hydrostatic pressure in a thermal environment is presented. The effective material properties of the inhomogeneous nanocomposite cylindrical shell are modeled on the basis of the extended mixture rule. Based on the effective material properties, the fundamental relations and stability equations are derived for thermal environments. In this process, the first-order shear deformation theory (FSDT) for the homogeneous orthotropic shell is generalized to the inhomogeneous shell theory. This is accomplished using the modified Donnell-type shell theory. The analytical expressions are obtained for hydrostatic buckling pressure of INCCSs in the framework of FSDT and classical shell theory (CST) by obtaining a solution based on Galerkin’s procedure. The numerical examples presented include both comparisons and original results. The last section shows the influences of carbon nanotube (CNT) models, volume fraction, and shell characteristics on the hydrostatic buckling pressure in the thermal environment.