scholarly journals Buckling and postbuckling of axially-loaded CNT-reinforced composite cylindrical shell surrounded by an elastic medium in thermal environment

2018 ◽  
Author(s):  
Hoang Van Tung
Keyword(s):  
Carbon Nanotubes ◽  
Elastic Medium ◽  
Volume Fraction ◽  
Effective Properties ◽  
Thermal Environment ◽  
Cylindrical Shells ◽  
Functionally Graded ◽  
Environment Temperature ◽  
Classical Shell Theory ◽  
Walled Carbon Nanotubes

Buckling and postbuckling behaviors of nanocomposite cylindrical shells reinforced by single walled carbon nanotubes (SWCNTs), surrounded by an elastic medium, exposed to a thermal environment and subjected to uniform axial compression are investigated in this paper. Material properties of carbon nanotubes (CNTs) and isotropic matrix are assumed to be temperature dependent, and effective properties of nanocomposite are estimated by extended rule of mixture. The CNTs are embedded into matrix via uniform distribution (UD) or functionally graded (FG) distribution along the thickness direction. Governing equations are based on Donnell’s classical shell theory taking into account von Karman-Donnell nonlinear terms and interaction between the shell and surrounding elastic medium. Three-term form of deflection and stress function are assumed to satisfy simply supported boundary conditions and Galerkin method is applied to obtain load-deflection relation from which buckling and postbuckling behaviors are analyzed. Numerical examples are carried out to analyze the effects of CNT volume fraction and distribution types, geometrical ratios, environment temperature and surrounding elastic foundation on the buckling loads and postbuckling strength of CNTRC cylindrical shells.

TORSIONAL BUCKLING OF FUNCTIONALLY GRADED CYLINDRICAL SHELLS WITH TEMPERATURE-DEPENDENT PROPERTIES

2013 ◽  
Vol 14 (01) ◽  
pp. 1350048 ◽  
Author(s):  
JIABIN SUN ◽  
XINSHENG XU ◽  
C. W. LIM
Keyword(s):  
Boundary Conditions ◽  
Volume Fraction ◽  
Effective Properties ◽  
Thermal Environment ◽  
Cylindrical Shells ◽  
Accurate Solution ◽  
Functionally Graded ◽  
Torsional Buckling ◽  
Temperature Dependent Properties ◽  
Transverse Boundary

Based on Hamilton's principle, a new accurate solution methodology is developed to study the torsional bifurcation buckling of functionally graded cylindrical shells in a thermal environment. The effective properties of functionally graded materials (FGMs) are assumed to be functions of the ambient temperature as well as the thickness coordinate of the shell. By applying Donnell's shell theory, the lower-order Hamiltonian canonical equations are established, from which the eigenvalues and eigenvectors are solved as the critical loads and buckling modes of the shell of concern, respectively. The effects of various aspects, including the combined in-plane and transverse boundary conditions, dimensionless geometric parameters, FGM parameters and changing thermal surroundings, are discussed in detail. The results reveal that the in-plane axial edge supports do have a certain influence on the buckling loads. On the other hand, the transverse boundary conditions only affect extremely short shells. With increasing thermal loads, the material volume fraction has a different influence on the critical stresses. It is concluded that the optimized FGM mixtures to withstand thermal torsional buckling are Si 3 N 4/SUS304 and Al 2 O 3/SUS304 among the materials studied in this paper.

scholarly journals Nonlinear Vibration Analysis of Functionally Graded Carbon Nanotube Reinforced Fluid-Conveying Tube in Thermal Environment

2021 ◽  
Author(s):  
Xu Chen ◽  
Jing-Lei Zhao ◽  
Gui-Lin She ◽  
Yan Jing ◽  
Huayan Pu ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Volume Fraction ◽  
Thermal Environment ◽  
Nonlinear Partial Differential Equations ◽  
Shear Deformation Theory ◽  
Functionally Graded ◽  
Nonlinear Frequency ◽  
Environment Temperature ◽  
Vibration Responses ◽  
Walled Carbon Nanotubes

Abstract In this paper, the nonlinear free vibration responses of functionally graded nanocomposite fluid-conveying tube reinforced by single-walled carbon nanotubes (SWNTs) in thermal environment is investigated. The SWCNTs gradient distributed in the thickness direction of the tube forms different reinforcement patterns. The materials properties of the functionally graded carbon nanotube-reinforced composites (FG-CNTRC) are estimated by rule of mixture. A higher-order shear deformation theory and Hamilton’s variational principle are employed to derive the motion equations incorporating the thermal and fluid effects. A two-step perturbation method is implemented to obtain the closed-form asymptotic solution for these nonlinear partial differential equations. The nonlinear frequency under several patterns of reinforcement are presented and discussed. We conducted a series of studies aimed at revealing the effects of the flow velocity, environment temperature, geometrical ratios and carbon nanotube volume fraction on the nature frequency.

Postbuckling behavior of CNT-reinforced composite cylindrical shell surrounded by an elastic medium and subjected to combined mechanical loads in thermal environments

2018 ◽  
Vol 32 (10) ◽  
pp. 1319-1346 ◽  
Author(s):  
Pham Thanh Hieu ◽  
Hoang Van Tung
Keyword(s):  
Carbon Nanotubes ◽  
Elastic Medium ◽  
Axial Compression ◽  
Lateral Pressure ◽  
Volume Fraction ◽  
Effective Properties ◽  
Cylindrical Shells ◽  
Nonlinear Load ◽  
Thermal Environments ◽  
Reinforced Composite

Cylindrical shells are usually buckled under complex and combined loading conditions. This article presents an analytical approach to investigate the buckling and postbuckling behaviors of cylindrical shells reinforced by single-walled carbon nanotubes, surrounded by an elastic medium, exposed to thermal environments, and subjected to combined axial compression and lateral pressure loads. Carbon nanotubes (CNTs) are imbedded into matrix phase by uniform distribution or functionally graded distribution along the thickness direction. The properties of constituents are assumed to be temperature dependent, and effective properties of CNT-reinforced composite (CNTRC) are determined by an extended rule of mixture. Governing equations are based on the classical shell theory (CST) taking von Karman–Donnell nonlinearity and surrounding elastic foundations into consideration. Three-term form of deflection is assumed to satisfy simply supported boundary conditions, and Galerkin method is applied to obtain nonlinear load–deflection relations from which buckling loads and postbuckling equilibrium paths are determined. Numerical examples are carried out to show the effects of CNT volume fraction, distribution types, thermal environments, preexisting nondestabilizing lateral pressure and axial compression loads, and elastic medium on the buckling and postbuckling behaviors of CNTRC cylindrical shells.

On the mechanical properties of functionally graded materials reinforced by carbon nanotubes

2017 ◽  
Vol 232 (9) ◽  
pp. 1632-1646 ◽  
Author(s):  
Saeed Rouhi ◽  
Seyed H Alavi
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Elastic Modulus ◽  
Functionally Graded Materials ◽  
Volume Fraction ◽  
Single Walled Carbon Nanotubes ◽  
Functionally Graded ◽  
Graded Materials ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes

In this paper, the elastic properties of functionally graded materials reinforced by single-walled carbon nanotubes are studied. Three different matrices, including steel-silicon, iron-alumina and alumina-zirconia are considered. Besides, the effects of nanotube length, radius and volume fraction on the Young’s modulus of functionally graded matrices reinforced by single-walled carbon nanotubes are investigated. It is observed that short nanotubes not only cannot increase the longitudinal elastic modulus of the matrices, but sometimes decrease their elastic modulus. Of the three selected matrices, steel-silicon matrix would have the most enhancement. Investigation of the effect of nanotube volume fraction on the mechanical properties of nanocomposites shows that increasing the volume fraction of long single-walled carbon nanotube results in increasing the elastic modulus of the nanocomposites.

scholarly journals Nonlinear buckling of CNT-reinforced composite toroidal shell segment surrounded by an elastic medium and subjected to uniform external pressure

2018 ◽  
Vol 40 (3) ◽  
pp. 285-301
Author(s):  
Hoang Van Tung ◽  
Pham Thanh Hieu
Keyword(s):  
Carbon Nanotubes ◽  
Elastic Medium ◽  
Volume Fraction ◽  
Effective Properties ◽  
Micromechanical Model ◽  
External Pressure ◽  
Toroidal Shell ◽  
Nonlinear Load ◽  
Uniform External Pressure ◽  
Reinforced Composite

Buckling and postbuckling behaviors of Toroidal Shell Segment (TSS) reinforced by single-walled carbon nanotubes (SWCNT), surrounded by an elastic medium and subjected to uniform external pressure are investigated in this paper. Carbon nanotubes (CNTs) are reinforced into matrix phase by uniform distribution (UD) or functionally graded (FG) distribution along the thickness direction. Effective properties of carbon nanotube reinforced composite (CNTRC) are estimated by an extended rule of mixture through a micromechanical model. Governing equations for TSSs are based on the classical thin shell theory taking into account geometrical nonlinearity and surrounding elastic medium. Three-term solution of deflection and stress function are assumed to satisfy simply supported boundary condition, and Galerkin method is applied to obtain nonlinear load-deflection relation from which buckling loads and postbuckling equilibrium paths are determined. The effects of CNT volume fraction, distribution types, geometrical ratios and elastic foundation on the buckling and postbuckling behaviors of CNTRC TSSs are analyzed and discussed.

scholarly journals Effect of Thickness Variable on the Bending Analysis of Rotating Functionally polymer Graded Carbon Nanotube Reinforced Cylindrical Panels

2019 ◽  
Vol 25 (4) ◽  
pp. 155-172
Author(s):  
Hamad Mohammed Hasan ◽  
Methaq Jasam Swadi
Keyword(s):  
Carbon Nanotubes ◽  
Variable Thickness ◽  
Volume Fraction ◽  
Shear Deformation Theory ◽  
Longitudinal Direction ◽  
Functionally Graded ◽  
Elastic Response ◽  
Good Correspondence ◽  
Cylindrical Panels ◽  
Walled Carbon Nanotubes

This study offers the elastic response of the variable thickness functionally graded (FG) by single walled carbon nanotubes reinforced composite (CNTRC) moderately thick cylindrical panels under rotating and transverse mechanical loadings. It’s considered that, three kinds of distributions of carbon nanotubes which are uniaxial aligned in the longitudinal direction and two functionally graded in the transverse direction of the cylindrical panels. Depending on first order shear deformation theory (FSDT), the governing equations can be derived. The partial differential equations are solved by utilizing the technique of finite element method (FEM) with a program has been built by using FORTRAN 95. The results are calculated to investigate the influence of the variable thickness, geometric parameters, rotating velocity, carbon nanotubes (CNTs) volume fraction for different boundary conditions on the non-dimensional deflection of the cylindrical panels. A comparison study has been carried out between the results of present study and that available in the open literature and found very good correspondence between the two results.  

Nonlinear thermal vibration and dynamic buckling of eccentrically stiffened sandwich-FGM cylindrical shells containing fluid

2018 ◽  
Vol 38 (6) ◽  
pp. 253-266
Author(s):  
Khuc Van Phu ◽  
Dao Huy Bich ◽  
Le Xuan Doan
Keyword(s):  
Thermal Environment ◽  
Cylindrical Shells ◽  
Geometrical Nonlinearity ◽  
Fluid Pressure ◽  
Dynamic Buckling ◽  
Functionally Graded ◽  
Dynamic Responses ◽  
Thermal Vibration ◽  
Foundation Model ◽  
Classical Shell Theory

The governing equations for analysing thermal vibration and dynamic buckling of eccentrically stiffened sandwich functionally graded cylindrical shells full filled with fluid and surrounded by elastic foundations in thermal environment are derived by using the classical shell theory, the geometrical nonlinearity in von Karman-Donnell sense, the smeared stiffener technique and Pasternak’s foundation model. Solutions of the problem are established according to the Galerkin’s method and Runge–Kutta method. The effects of fluid pressure, stiffeners, geometrical ratios, temperature and elastic foundation on the dynamic responses of shells are investigated.

Nonlinear approach on torsional buckling and postbuckling of functionally graded cylindrical shells reinforced by orthogonal and spiral stiffeners in thermal environment

2018 ◽  
Vol 233 (6) ◽  
pp. 2091-2106 ◽  
Author(s):  
Nguyen Thi Phuong ◽  
Dang Thanh Luan ◽  
Vu Hoai Nam ◽  
Pham Thanh Hieu
Keyword(s):  
Volume Fraction ◽  
Thermal Environment ◽  
Cylindrical Shells ◽  
Geometrical Nonlinearity ◽  
Functionally Graded ◽  
Postbuckling Behavior ◽  
Distribution Models ◽  
Torsional Buckling ◽  
Nonlinear Approach ◽  
Torsional Stability

A new nonlinear approach on the buckling and postbuckling of functionally graded orthogonal and/or spiral-stiffened circular cylindrical shells subjected to torsional loads is proposed in this paper. The shells skin are stiffened by eccentrically rings, stringers, and/or spiral stiffeners at the surface of shells assuming that the material distribution laws of shell skin and stiffeners are graded by two distribution models. Lekhnitskii’s smeared stiffeners technique is improved for spiral stiffeners with effect of thermal terms. This is the significant novelty and scientific contribution of this paper. Theoretical formulations were established by using the Donnell shell theory taking into account the geometrical nonlinearity of von Kármán. The obtained results investigated in numerical forms show effects of volume fraction exponent of shell skin and stiffeners, geometrical parameter and stiffeners on the torsional buckling, and postbuckling behavior of functionally graded cylindrical shells. Especially, very large effects of spiral stiffeners on torsional stability behavior are obtained in comparison with same quantity material of orthogonal stiffeners.

scholarly journals Magneto-Thermo-Mechanical Buckling Analysis of Mindlin Plate Reinforced with FG-Carbon Nanotubes

2016 ◽  
Vol 62 (3) ◽  
pp. 89-104
Author(s):  
R. Kolahchi ◽  
M. Esmailpour ◽  
M. Safari
Keyword(s):  
Magnetic Field ◽  
Carbon Nanotubes ◽  
Elastic Medium ◽  
Plate Theory ◽  
Buckling Analysis ◽  
Functionally Graded ◽  
Mindlin Plate ◽  
Temperature Dependent ◽  
Distribution Type ◽  
Walled Carbon Nanotubes

Abstract A buckling analysis of temperature-dependent embedded plates reinforced by single-walled carbon nanotubes (SWCNTs) subjected to a magnetic field is investigated. The SWCNTs are distributed as uniform (UD) and three types of functionally graded nanotubes (FG), in which the material properties of the nano-composite plate are estimated based on the mixture rule. The surrounding temperature-dependent elastic medium is simulated as Pasternak foundation. Based on the orthotropic Mindlin plate theory, the governing equations are derived using Hamilton's principle. The buckling load of the structure is calculated based on an exact solution by the Navier method. The influences of elastic medium, magnetic field, temperature and distribution type, and volume fractions of SWCNT are shown on the buckling of the plate. Results indicate that CNT distribution close to the top and bottom are more efficient than that distributed near the mid-plane for increasing the stiffness of the plates.

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