Torsional instability of carbon nano-peapods based on the nonlocal elastic shell theory

2013 ◽  
Vol 47 ◽  
pp. 316-323 ◽  
Author(s):  
M. Asghari ◽  
J. Rafati ◽  
R. Naghdabadi
Keyword(s):  
Shell Theory ◽  
Elastic Shell ◽  
Torsional Instability

Analysis of Spectral Characteristics of Sound Waves Scattered from a Cracked Cylindrical Elastic Shell Filled with a Viscous Fluid

2013 ◽  
Vol 38 (3) ◽  
pp. 335-350 ◽  
Author(s):  
Olexa Piddubniak ◽  
Nadia Piddubniak
Keyword(s):  
Viscous Fluid ◽  
Shell Theory ◽  
Elastic Shell ◽  
Spectral Characteristics ◽  
Steel Shell ◽  
Sound Waves ◽  
Thin Cylindrical Shell ◽  
Shell Surface ◽  
Theory Approximation ◽  
Directivity Patterns

Abstract The scattering of plane steady-state sound waves from a viscous fluid-filled thin cylindrical shell weak- ened by a long linear slit and submerged in an ideal fluid is studied. For the description of vibrations of elastic objects the Kirchhoff-Love shell-theory approximation is used. An exact solution of this problem is obtained in the form of series with cylindrical harmonics. The numerical analysis is carried out for a steel shell filled with oil and immersed in seawater. The modules and phases of the scattering amplitudes versus the dimensionless wavenumber of the incident sound wave as well as directivity patterns of the scattered field are investigated taking into consideration the orientation of the slit on the elastic shell surface. The plots obtained show a considerable influence of the slit and viscous fluid filler on the diffraction process.

Local loads on a toroidal shell

1992 ◽  
Vol 27 (2) ◽  
pp. 59-66 ◽  
Author(s):  
D Redekop ◽  
F Zhang
Keyword(s):  
Cylindrical Shell ◽  
Shell Theory ◽  
Elastic Shell ◽  
Toroidal Shell ◽  
Pipe Bend ◽  
Local Loads ◽  
Simply Supported ◽  
Linear Elastic ◽  
Wide Range ◽  
Theory Solution

In this study the effect of local loads applied on a sectorial toroidal shell (pipe bend) is considered. A linear elastic shell theory solution for local loads is first outlined. The solution corresponds to the case of a shell simply supported at the two ends. Detailed displacement and stress results are then given for a specific shell with loadings centred at three positions; the crown circles, the extrados, and the intrados. These results are compared with results for a corresponding cylindrical shell. The paper concludes with a table summarizing results for characteristic displacements and stresses in a number of shells, covering a wide range of geometric parameters.

scholarly journals Applicability and Limitations of Simplified Elastic Shell Theories for Vibration Modelling of Double-Walled Carbon Nanotubes

2021 ◽  
Vol 7 (3) ◽  
pp. 61
Author(s):  
Matteo Strozzi ◽  
Oleg V. Gendelman ◽  
Isaac E. Elishakoff ◽  
Francesco Pellicano
Keyword(s):  
Carbon Nanotubes ◽  
Shell Theory ◽  
Cylindrical Shells ◽  
Ritz Method ◽  
Elastic Shell ◽  
Mode Shapes ◽  
Simplified Models ◽  
Circular Cylindrical Shells ◽  
Double Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The applicability and limitations of simplified models of thin elastic circular cylindrical shells for linear vibrations of double-walled carbon nanotubes (DWCNTs) are considered. The simplified models, which are based on the assumptions of membrane and moment approximate thin-shell theories, are compared with the extended Sanders–Koiter shell theory. Actual discrete DWCNTs are modelled by means of couples of concentric equivalent continuous thin, circular cylindrical shells. Van der Waals interaction forces between the layers are taken into account by adopting He’s model. Simply supported and free–free boundary conditions are applied. The Rayleigh–Ritz method is considered to obtain approximate natural frequencies and mode shapes. Different aspect and thickness ratios, and numbers of waves along longitudinal and circumferential directions, are analysed. In the cases of axisymmetric and beam-like modes, it is proven that membrane shell theory, differently from moment shell theory, provides results with excellent agreement with the extended Sanders–Koiter shell theory. On the other hand, in the case of shell-like modes, it is found that both membrane and moment shell theories provide results reporting acceptable agreement with the extended Sanders–Koiter shell theory only for very limited ranges of geometries and wavenumbers. Conversely, for shell-like modes it is found that a newly developed, simplified shell model, based on the combination of membrane and semi-moment theories, provides results in satisfactory agreement with the extended Sanders–Koiter shell theory in all ranges.

A Finite Element Model for Bending Buckling of Single Wall Carbon Nano-Tubes and Investigation of Geometrical Parameters on it

2008 ◽  
Author(s):  
Ali Hemmasizadeh ◽  
Reza Kamali ◽  
Ehsan Hadi ◽  
Rasoul Khandan
Keyword(s):  
Finite Element ◽  
Shell Theory ◽  
Elastic Shell ◽  
Single Walled Carbon Nanotubes ◽  
Element Model ◽  
Dynamics Simulation ◽  
Geometrical Parameters ◽  
Buckling Behavior ◽  
Carbon Nano Tubes ◽  
Walled Carbon Nanotubes

Bending buckling behavior of single-walled carbon nanotubes (SWCNTs) is modeled by means of finite element method (FEM) and the relations between critical bending buckling curvature and geometrical parameters of nanotubes are determined. Elastic modulus and wall thickness of nanotubes are chosen in a way that elastic shell theory is capable of predicting mechanical properties of nanotubes. The effect of initial internal stress state through the shell thickness is investigated. Computed results are very close to the results of molecular dynamics simulation.

scholarly journals DESIGN OF CONCRETE CHIMNEYS VIA BEAM THEORY AND NONLINEAR SHELL ANALYSIS

2016 ◽  
Vol 7 ◽  
pp. 79-84
Author(s):  
Franziska Wehr ◽  
Reinhard Harte
Keyword(s):  
Bearing Capacity ◽  
Shell Theory ◽  
Elastic Shell ◽  
Beam Theory ◽  
Nonlinear Material ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Linear Elastic ◽  
Shell Analysis ◽  
Safe Side

This paper compares the load-bearing capacity of chimneys calculated via beam and shell theory. It becomes apparent that the design via beam theory is on the safe side for the vertical reinforcement of the chosen examples for h/d ratios larger than 30. For non-slender chimneys the design via beam theory overestimates the load distribution around the circumference and yields to wrong results. On the other hand a linear elastic shell calculation underestimates the load-bearing capacity of the chimney. However a realistic distribution of stresses in the cross section of a chimney can still be calculated using shell theory with nonlinear material properties.

Elasto/Visco-Plastic Dynamic Response of Axisymmetrical Shells by Overlay Model

1980 ◽  
Vol 102 (3) ◽  
pp. 257-263 ◽  
Author(s):  
S. Takezono ◽  
K. Tao ◽  
K. Kanezaki
Keyword(s):  
Dynamic Response ◽  
Bauschinger Effect ◽  
Shell Theory ◽  
Elastic Shell ◽  
Isotropic Hardening ◽  
Time Varying ◽  
Plastic Range ◽  
Rate Dependency ◽  
The Finite Difference Method ◽  
Overlay Model

The numerical analysis of the elasto/visco-plastic dynamic response of the axisymmetrical shells to the time-varying load is carried out by the use of the elasto/visco-plastic overlay model which is able to express the Bauschinger effect and the strain rate dependency. Namely Perzyna’s equation is used for the constitutive relation of each layer of the overlay model and as a whole, the Bauschinger effect and the influence of viscosity in plastic range of the materials are taken into account. The basic differential equations for the shells subjected to axisymmetrical loads are derived by extending Sanders’ elastic shell theory and the equations are numerically solved by the finite difference method. As a numerical example, the pressure vessel under semi-sinusoidal pressure load with respect to time is analyzed and the results are compared with ones in the case of isotropic hardening.

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