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A H Sofiyev - One of the best experts on this subject based on the ideXlab platform.
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the stability of fgm truncated Conical Shells under combined axial and external mechanical loads in the framework of the shear deformation theory
Composites Part B-engineering, 2016Co-Authors: A H Sofiyev, N KuruogluAbstract:Abstract The major goal of this research was to obtain a closed form of the solution for critical combined loads (combined effects of the axial load and l lateral pressure or the axial load and hydrostatic pressure) of functionally graded (FG) truncated Conical Shell in the framework of the shear deformation theory (SDT). The basic equations of FG truncated Conical Shell Shells subjected to the combined loads are derived in the framework of the SDT. By using the Galerkin method to basic equations are obtained the expressions for critical combined loads of FG truncated Conical Shell in the framework of the SDT. In particular, similar expressions in the framework of the classical Shell theory (CST) are obtained, also. Our numerical experiments reveal that the proposed solution may offer accurate critical combined loads for the FGM Shells as compared with reference solutions available in the literature. Finally, the calculation and presentation of the effects of many parameters included in the analysis conclude the goals to be reached in the study.
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on the dynamic buckling of truncated Conical Shells with functionally graded coatings subject to a time dependent axial load in the large deformation
Composites Part B-engineering, 2014Co-Authors: A H SofiyevAbstract:Abstract A study has been made to determine the critical time parameters of truncated Conical Shells with functionally graded coatings (FGCs) and subjected to a time dependent axial load in the large deformation. The method of solution utilizes Superposition principle and Galerkin procedure. Donnell–Karman type non-linear differential equations for the truncated Conical Shell with FGCs are derived and reduced to ordinary differential equation with the time dependent coefficient. The Runge–Kutta method and modified Budiansky–Roth criterion are then used to solve this non-linear differential equation with the time dependent coefficient. Finally, effects of compositional profiles of coatings, variation of truncated Conical Shell parameters and loading speed on the dimensionless linear and non-linear critical time parameters have been studied. Comparing the results of this study with those in the literature validates the present analysis.
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non linear dynamic analysis of symmetric and antisymmetric cross ply laminated orthotropic thin Shells
Meccanica, 2014Co-Authors: A M Najafov, A H Sofiyev, David Hui, Fethi Kadioglu, N V Dorofeyskaya, He HuangAbstract:In this paper, the governing equations for non-linear free vibration of truncated, thin, laminated, orthotropic Conical Shells using the theory of large deformations with the Karman-Donnell-type of kinematic nonlinearity are derived. Applying superposition principle and Galerkin’s method, these equations are reduced to a time dependent non-linear differential equation. The frequency-amplitude relationship for the laminated orthotropic thin truncated Conical Shell is obtained using the method of weighted residuals. In the particular case, we can obtain the similar relationships for the single-layer and laminated orthotropic cylindrical Shells, also. The influence played by geometrical parameters of the Conical Shell and physical parameters of the laminate (i.e. material properties, staking sequences and number of layers) on the non-linear vibration behavior of the Conical Shell is examined. It is noticed that the non-linear vibration of Shells is highly dependent on laminate characteristics and, from these observations, it is concluded that specific configurations of laminates should be designed for each kind of application. Present results are compared with available data for special cases.
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the influence of non homogeneity on the frequency amplitude characteristics of laminated orthotropic truncated Conical Shell
Composite Structures, 2014Co-Authors: A H SofiyevAbstract:Abstract In this study, the non-linear vibration of laminated non-homogenous orthotropic truncated Conical Shell is investigated. It is assumed that the Young’s moduli, shear modulus and density of the layers of the Shell vary exponentially through the thickness direction. The basic equations of laminated non-homogenous orthotropic truncated Conical Shells are derived using the large deformation theory with von Karman–Donnell-type of kinematic non-linearity. The non-linear basic equations are reduced to the non-linear differential equation depending on the time using the superposition principle and Galerkin method. This equation is solved using semi-inverse method and is found the frequency–amplitude relationship. Finally, carrying out some computations, the effects of non-homogeneity, number and ordering of layers, and Conical Shell characteristics on frequency–amplitude characteristics have been studied.
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non linear buckling of an fgm truncated Conical Shell surrounded by an elastic medium
International Journal of Pressure Vessels and Piping, 2013Co-Authors: N Kuruoglu, A H SofiyevAbstract:Abstract In this paper, the non-linear buckling of the truncated Conical Shell made of functionally graded materials (FGMs) surrounded by an elastic medium has been studied using the large deformation theory with von Karman–Donnell-type of kinematic non-linearity. A two-parameter foundation model (Pasternak-type) is used to describe the Shell–foundation interaction. The FGM properties are assumed to vary continuously through the thickness direction. The fundamental relations, the modified Donnell type non-linear stability and compatibility equations of the FGM truncated Conical Shell resting on the Pasternak-type elastic foundation are derived. By using the Superposition and Galerkin methods, the non-linear stability equations for the FGM truncated Conical Shell is solved. Finally, influences of variations of Winkler foundation stiffness and shear subgrade modulus of the foundation, compositional profiles and Shell characteristics on the dimensionless critical non-linear axial load are investigated. The present results are compared with the available data for a special case.
K Y Lam - One of the best experts on this subject based on the ideXlab platform.
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generalized differential quadrature for free vibration of rotating composite laminated Conical Shell with various boundary conditions
International Journal of Mechanical Sciences, 2003Co-Authors: K Y LamAbstract:By using the generalized differential quadrature (GDQ) method, this paper presents the orthotropic influence of composite materials on frequency characteristics for a rotating thin truncated circular symmetrical cross-ply laminated composite Conical Shell with different boundary conditions. The present governing equations of free vibration include the effects of initial hoop tension and the centrifugal and Coriolis accelerations due to rotation. Frequency characteristics are obtained to study in detail the orthotropic influences. Effects of boundary condition, rotating speed, circumferential wave number and geometric property are also discussed. To ensure the accuracy of the present results by the GDQ method, comparisons are made with those available in open literature and very good agreements are achieved.
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orthotropic influence on frequency characteristics of a rotating composite laminated Conical Shell by the generalized differential quadrature method
International Journal of Solids and Structures, 2001Co-Authors: Li Hua, K Y LamAbstract:By using the generalized differential quadrature (GDQ) method, this paper presents the influence of orthotropic material on the frequency characteristics for a rotating thin truncated circular symmetrical cross-ply laminated composite Conical Shell with simply-supported boundary conditions at both edges. The present analysis includes the effects of initial hoop tension and the centrifugal and coriolis accelerations due to rotation. Frequency characteristics is obtained for various orthotropic parameters; the orthotropic influences of material on the frequency characteristics are also discussed for different cone angles. To validate the accuracy and efficiency of present analysis by the GDQ method, comparisons are made with those available in open literature; very good agreements are achieved.
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influence of boundary conditions on the frequency characteristics of a rotating truncated circular Conical Shell
Journal of Sound and Vibration, 1999Co-Authors: K Y Lam, Li HuaAbstract:The influence of boundary conditions on the frequency characteristics of a rotating Conical Shell is studied using the Galerkin method. The results obtained include the relationships between the frequency parameter and circumferential wavenumber and between the frequency parameter and rotating velocity at various cone angles under different boundary conditions. The variation of the frequency characteristics at various vibrational modes is also shown. In order to validate the present analysis, several comparisons of the numerical results with those published are made. One comparison is for an infinitely long rotating cylindrical Shell; other comparisons are for the non-rotating Conical Shells. As is expected, these comparisons show very good agreement.
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on free vibration of a rotating truncated circular orthotropic Conical Shell
Composites Part B-engineering, 1999Co-Authors: K Y Lam, Li HuaAbstract:Abstract This article presents a method to study the free vibration of a rotating truncated circular orthotropic Conical Shell with simply-supported boundary conditions at both ends. Based on the Love first approximation theory and considering the centrifugal and Coriolis accelerations as well as the initial hoop tension, this article studies the frequency characteristics for various geometric and material properties. A detailed discussion is also made for the effects of material orthotropy and cone angle on the frequency characteristics. The present method proves to be reliable and accurate by comparing with available results in the literature.
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vibration analysis of a rotating truncated circular Conical Shell
International Journal of Solids and Structures, 1997Co-Authors: K Y Lam, Li HuaAbstract:Abstract In this paper, a method is presented to study the free vibrations of a rotating truncated circular Conical Shell with simply-supported boundary conditions. The method is based on the use of Love’s first approximation theory and it includes the effects of initial hoop tension and the centrifugal and coriolis accelerations. Results are obtained for the frequency characteristics at different modes and various geometric properties, the effects of cone angle on the frequency characteristics are also discussed. To validate the present analysis, comparisons are made with a very long rotating cylindrical Shell and a non-rotating truncated circular Conical Shell and very good agreement is obtained.
Li Hua - One of the best experts on this subject based on the ideXlab platform.
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orthotropic influence on frequency characteristics of a rotating composite laminated Conical Shell by the generalized differential quadrature method
International Journal of Solids and Structures, 2001Co-Authors: Li Hua, K Y LamAbstract:By using the generalized differential quadrature (GDQ) method, this paper presents the influence of orthotropic material on the frequency characteristics for a rotating thin truncated circular symmetrical cross-ply laminated composite Conical Shell with simply-supported boundary conditions at both edges. The present analysis includes the effects of initial hoop tension and the centrifugal and coriolis accelerations due to rotation. Frequency characteristics is obtained for various orthotropic parameters; the orthotropic influences of material on the frequency characteristics are also discussed for different cone angles. To validate the accuracy and efficiency of present analysis by the GDQ method, comparisons are made with those available in open literature; very good agreements are achieved.
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influence of boundary conditions on the frequency characteristics of a rotating truncated circular Conical Shell
Journal of Sound and Vibration, 1999Co-Authors: K Y Lam, Li HuaAbstract:The influence of boundary conditions on the frequency characteristics of a rotating Conical Shell is studied using the Galerkin method. The results obtained include the relationships between the frequency parameter and circumferential wavenumber and between the frequency parameter and rotating velocity at various cone angles under different boundary conditions. The variation of the frequency characteristics at various vibrational modes is also shown. In order to validate the present analysis, several comparisons of the numerical results with those published are made. One comparison is for an infinitely long rotating cylindrical Shell; other comparisons are for the non-rotating Conical Shells. As is expected, these comparisons show very good agreement.
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on free vibration of a rotating truncated circular orthotropic Conical Shell
Composites Part B-engineering, 1999Co-Authors: K Y Lam, Li HuaAbstract:Abstract This article presents a method to study the free vibration of a rotating truncated circular orthotropic Conical Shell with simply-supported boundary conditions at both ends. Based on the Love first approximation theory and considering the centrifugal and Coriolis accelerations as well as the initial hoop tension, this article studies the frequency characteristics for various geometric and material properties. A detailed discussion is also made for the effects of material orthotropy and cone angle on the frequency characteristics. The present method proves to be reliable and accurate by comparing with available results in the literature.
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vibration analysis of a rotating truncated circular Conical Shell
International Journal of Solids and Structures, 1997Co-Authors: K Y Lam, Li HuaAbstract:Abstract In this paper, a method is presented to study the free vibrations of a rotating truncated circular Conical Shell with simply-supported boundary conditions. The method is based on the use of Love’s first approximation theory and it includes the effects of initial hoop tension and the centrifugal and coriolis accelerations. Results are obtained for the frequency characteristics at different modes and various geometric properties, the effects of cone angle on the frequency characteristics are also discussed. To validate the present analysis, comparisons are made with a very long rotating cylindrical Shell and a non-rotating truncated circular Conical Shell and very good agreement is obtained.
Q Wang - One of the best experts on this subject based on the ideXlab platform.
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on dynamic instability of a pressurized functionally graded carbon nanotube reinforced truncated Conical Shell subjected to yawed supersonic airflow
Composite Structures, 2016Co-Authors: M Mehri, Hamed Asadi, Q WangAbstract:Abstract The aeroelastic flutter characteristics of a functionally graded carbon nanotube reinforced composite (FG-CNTRC) truncated Conical Shell under simultaneous actions of a hydrostatic pressure and yawed supersonic airflow are scrutinized. The nonlinearity in geometry of the Conical Shell is considered in Green–Lagrange sense and the model is derived according to the Novozhilov nonlinear Shell theory. The aerodynamic pressure is modeled based on the quasi-steady Krumhaar’s modified supersonic piston theory by considering the effect of the panel curvature and flow yaw angle. Parametric studies are conducted to investigate the effects of boundary conditions, semi-vertex angle, distribution and volume fraction of CNT, Mach number and airflow yaw angle on the stability boundaries and flutter characteristics. The results show that the semi-vertex angle and CNT distribution may alter the stability boundaries. It is also found that the aeroelastic flutter responses of the structure can be significantly improved through a functionally graded distribution of CNT in a polymer matrix. Moreover, the aeroelastic characteristics of the FG-CNTRC truncated Conical Shell are found to be very sensitive to geometrical parameters and the airflow yaw angle. The results of this study shed a light into developing and using ultra-high-strength and low-weight composites reinforced with CNT for aerospace applications.
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buckling and vibration analysis of a pressurized cnt reinforced functionally graded truncated Conical Shell under an axial compression using hdq method
Computer Methods in Applied Mechanics and Engineering, 2016Co-Authors: M Mehri, Hamed Asadi, Q WangAbstract:Abstract The present research deals with bifurcation and vibration responses of a composite truncated Conical Shell with embedded single-walled carbon nanotubes (SWCNTs) subjected to an external pressure and axial compression simultaneously. The distribution of reinforcements through the thickness of the Shell is assumed to be either uniform or functionally graded. The equations of motion are established using Green–Lagrange type nonlinear kinematics within the framework of Novozhilov nonlinear Shell theory. Linear membrane prebuckling analysis is conducted to extract the prebuckling deformations. The stability equations are derived by applying the adjacent equilibrium criterion to the prebuckling state of the Conical Shell. A semi-analytical solution on the basis of the trigonometric expansion through the circumferential direction along with the harmonic differential quadrature (HDQ) discretization in the meridional direction is developed. A series of comparison studies are carried out to assure the accuracy and the convergence of the HDQ method. The research indicates that the superb accuracy and efficiency of solutions with few grid points are attributed to the higher-order harmonic approximation function in the HDQ method. Parametric studies are also presented to investigate the influence of boundary conditions, semi-vertex angle of the cone, volume fraction and distribution of CNTs on stability and vibration characteristics of the truncated Conical Shell. The results show that both volume fraction and distribution of CNTs play a pivotal role in the natural frequencies, buckling mode and buckling loads of the FG-CNTRC truncated Conical Shell.
K M Liew - One of the best experts on this subject based on the ideXlab platform.
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an element free analysis of mechanical and thermal buckling of functionally graded Conical Shell panels
International Journal for Numerical Methods in Engineering, 2011Co-Authors: X Zhao, K M LiewAbstract:This paper presents a mechanical and thermal buckling analysis of metal and ceramic functionally graded Conical Shell panels using the element-free kp-Ritz method. The formulation is based on the first-order shear deformation Shell theory, which accounts for the transverse shear strains and rotary inertia, and mesh-free kernel particle functions are employed to approximate the two-dimensional displacement fields. The effective material properties of the functionally graded Conical Shell panels are assumed to be smooth and continuous through their thickness direction, and are determined according to a power-law distribution of the volume fractions of their constituents. Convergence studies are performed in terms of the number of nodes, and comparisons between the current solutions and those reported in the literature are provided to verify the accuracy of the proposed method. Three types of functionally graded Conical Shell panels, Al/ZrO2, SUS304/Si3N4, and Al2O3/Ti−6Al−4V are selected for study, and the effects of the volume fraction, boundary condition, semi-vertex angle, length-to-thickness ratio, and temperature-dependent material properties on the buckling strength are discussed in detail. Copyright © 2010 John Wiley & Sons, Ltd.
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free vibration analysis of functionally graded Conical Shell panels by a meshless method
Composite Structures, 2011Co-Authors: X Zhao, K M LiewAbstract:A free vibration analysis of metal and ceramic functionally graded Conical Shell panels is presented using the element-free kp-Ritz method. The first-order shear deformation Shell theory is used to account for the transverse shear strains and rotary inertia, and mesh-free kernel particle functions are employed to approximate the two-dimensional displacement fields. The material properties of the Conical Shell panels are assumed to vary continuously through their thickness in accordance with a power-law distribution of the volume fractions of their constituents. Convergence studies are performed in terms of the number of nodes, and comparisons of the current solutions and those reported in literature are provided to verify the accuracy of the proposed method. Two types of functionally graded Conical Shell panels, including Al/ZrO2 and Ti–6Al–4V/aluminum oxide, are chosen in the study, and the effects of the volume fraction, boundary condition, semi-vertex angle, and length-to-thickness ratio on their frequency characteristics are discussed in detail.
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vibration characteristics of Conical Shell panels with three dimensional flexibility
Journal of Applied Mechanics, 2000Co-Authors: K M Liew, Z C FengAbstract:A first known investigation on the three-dimensional vibration characteristics of Conical Shell panels is reported. A linear frequency equation is derived based on an exact three-dimensional, small-strain, linearly elastic theory. Sets of one and two-dimensional polynomial series are employed to approximate the spatial displacements of the Conical Shell panels in three dimension. The perturbation of frequency responses due to the variations of relative thickness L/h, slanted length L/S, vertex angle γ v , and subtended angle γ o is investigated. First known frequency parameters and three-dimensional deformed mode shapes of the Conical Shell panels are presented in vivid graphical forms. The new results may serve as benchmark references for validating the new refined Shell theories and new computational techniques.