Vibration Characteristics of the Respiratory Branched Network-Comparative Study

2005 ◽  
Author(s):  
P. M. Au ◽  
A. M. Al-Jumaily
Keyword(s):  
Boundary Conditions ◽  
Comparative Study ◽  
Circular Cylindrical Shell ◽  
Vibration Characteristics ◽  
The Finite Element Method ◽  
Resonant Frequencies ◽  
Membrane Shell ◽  
Classical Boundary ◽  
Circular Cylindrical Shells ◽  
Shell Approximation

Determining the vibration characteristics of a realistic branched biological network, such as the respiratory system, faces many hurdles, which includes using the appropriate theory, specifying suitable boundary conditions and selecting accurate physical properties. Further, dichotomized or bifurcated structures beyond a simple circular cylindrical shell induce problems and difficulties in boundary matching between generations. This paper determines the natural frequencies using the Donnell-Mushtari formulation, membrane-shell approximation, a simplified limiting ring formula and the finite element method using COSMOS/Works™ for circular cylindrical shells with classical boundary conditions. Some experimental data are used for comparison and validation. Comparative study between the various methods sets the pros, cons, limitations of each method and the boundaries for the resonant frequencies of each individual generation of this system.

scholarly journals Vibration Characteristics of Ring-Stiffened Functionally Graded Circular Cylindrical Shells

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Muhmmad Nawaz Naeem ◽  
Shazia Kanwal ◽  
Abdul Ghafar Shah ◽  
Shahid Hussain Arshad ◽  
Tahir Mahmood
Keyword(s):  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Vibration Characteristics ◽  
Functionally Graded ◽  
Lagrangian Function ◽  
Dynamical Equations ◽  
Graded Materials ◽  
Present Technique ◽  
Circular Cylindrical Shells ◽  
Stiffened Cylindrical Shells

The vibration characteristics of ring stiffened cylindrical shells are analyzed. These shells are assumed to be structured from functionally graded materials (FGM) and are stiffened with isotropic rings. The problem is formulated by coupling the expressions for strain and kinetic energies of a circular cylindrical shell with those for rings. The Lagrangian function is framed by taking difference of strain and kinetic energies. The Rayleigh-Ritz approach is employed to obtain shell dynamical equations. The axial model dependence is approximated by characteristic beam functions that satisfy the boundary conditions. The validity and efficiency of the present technique are verified by comparisons of present results with the previous ones determined by other researchers.

Buckling of Composite and Homogeneous Isotropic Cylindrical Shells Under Axial and Radial Loading

1969 ◽  
Vol 36 (4) ◽  
pp. 791-798 ◽  
Author(s):  
M. M. Lei ◽  
Shun Cheng
Keyword(s):  
Boundary Conditions ◽  
Axial Compression ◽  
Circular Cylindrical Shell ◽  
Radial Pressure ◽  
Buckling Load ◽  
Simply Supported ◽  
Classical Boundary ◽  
Axial Compressive Stress ◽  
Radial Loading ◽  
Geometrical Dimensions

A theoretical analysis of the buckling of a multilayered thin orthotropic composite circular cylindrical shell of finite length, subjected to (a) uniform axial compression, and (b) axial compression combined with radial pressure, is presented. At each end of the shell, four boundary conditions are satisfied. Four combinations of boundary conditions for simply supported shells, and four combinations of boundary conditions for clamped shells, are treated. These boundary conditions are reduced to the vanishing of a fourth-order determinant. Buckling loads for boron-epoxy composite shells are determined and the results are shown in a series of diagrams. The effect of boundary conditions on the buckling load for various geometrical dimensions of composite cylinders is investigated. Details of the boundary conditions are shown to have strong influence on the buckling load of the shell. The minimum critical axial compression for a simply supported shell with boundary conditions SS1 is as low as 79 percent of the minimum critical axial compression for a shell with classical boundary conditions SS3. As a special case of a composite shell, the minimum critical axial compressive stress for a homogeneous, isotropic, simply supported shell with end conditions SS1 is found to be 43.7 percent of the classical critical stress.

Vibrations of Circular Cylindrical Shells under External Water Pressure

1992 ◽  
Vol 206 (2) ◽  
pp. 79-86 ◽  
Author(s):  
C T F Ross ◽  
T Johns ◽  
R M Stanton
Keyword(s):  
Water Pressure ◽  
Cylindrical Shells ◽  
Shell Element ◽  
The Finite Element Method ◽  
Applied Water ◽  
Resonant Frequencies ◽  
External Water Pressure ◽  
Circular Cylindrical Shells ◽  
External Water ◽  
Surrounding Fluid

A theoretical and an experimental investigation was made on the vibration of three machined circular cylindrical shells under external water pressure. The theoretical investigation was based on the finite element method, where the shell was modelled by a truncated thin-walled conical shell element and the surrounding fluid by an annular element which had a cross-section in the form of an eight-node isoparametric quadrilateral. Comparison between theory and experiment was good and showed that the resonant frequencies decreased with an increase in the externally applied water pressure.

scholarly journals STABILITY OF ROTATING CIRCULAR CYLINDRICAL SHELL SUBJECT TO AN AXIAL AND ROTATIONAL FLUID FLOW

2017 ◽  
Vol 18 (9) ◽  
pp. 84-97
Author(s):  
S.A. Bochkarev ◽  
V.P. Matveenko
Keyword(s):  
Finite Element Method ◽  
Fluid Flow ◽  
Boundary Conditions ◽  
Circular Cylindrical Shell ◽  
Loss Of Stability ◽  
Rotating Fluid ◽  
The Finite Element Method ◽  
The Stability ◽  
Rotating Shell ◽  
Simultaneous Rotation

This paper is concerned with the stability analysis of rotating cylindrical shells conveying a co-rotating fluid. The problem is solved by the finite element method for shells subjected to different boundary conditions. It has been found that the loss of stability for a rotating shell under the action of the fluid having both axial and circumferential velocity components depends on the type of boundary conditions imposed on the shell ends. The results of numerical calculations have shown that for different variants of boundary conditions a simultaneous rotation of shell and the fluid causes an increase or decrease in the critical velocity of axial fluid flow.

Analysis of Fiberglass Winding Angle on Natural Frequency of Cylindrical Shell with Symmetric Boundary Conditions

2013 ◽  
Vol 765-767 ◽  
pp. 106-109
Author(s):  
Zhi Wei Wang ◽  
Yan Fu Wang ◽  
Bai Qin
Keyword(s):  
Cylindrical Shell ◽  
Free Vibration ◽  
Boundary Conditions ◽  
Natural Frequency ◽  
Circular Cylindrical Shell ◽  
Glass Fiber Reinforced Plastic ◽  
Glass Fiber Reinforced ◽  
Reinforced Plastic ◽  
Circular Cylindrical Shells ◽  
Winding Angle

In order to obtain approximate solution of natural frequencies for the free vibration of anisotropic circular cylindrical shells made of GFRP (glass fiber-reinforced plastic) with symmetric boundary conditions, Loves theory and energy method are used. Computation results show that the fundamental natural frequency comes from different vibration modes while the winding angle varies, the effect of number of axial half waves is stronger than number of circumferential waves on natural frequency of free vibration of anisotropic circular cylindrical shell.

Vibrations of Circular Cylindrical Shells With General Elastic Boundary Restraints

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
W. L. Li
Keyword(s):  
Boundary Conditions ◽  
Solution Method ◽  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Elastic Boundary ◽  
Special Cases ◽  
Ritz Procedure ◽  
Circular Cylindrical Shells ◽  
Elastically Restrained ◽  
Structural Engineers

Vibration of a circular cylindrical shell with elastic boundary restraints is of interest to both researchers and structural engineers. This class of problems, however, is far less attempted in the literature than its counterparts for beams and plates. In this paper, a general solution method is presented for the vibration analysis of cylindrical shells with elastic boundary supports. This method universally applies to shells with a wide variety of boundary conditions including all 136 classical (homogeneous) boundary conditions which represent the special cases when the stiffnesses for the restraining springs are set as either zero or infinity. The Rayleigh–Ritz procedure based on the Donnell–Mushtari theory is utilized to find the displacement solutions in the form of the modified Fourier series expansions. Numerical examples are given to demonstrate the accuracy and reliability of the current solution method. The modal characteristics of elastically restrained shells are discussed against different supporting stiffnesses and configurations.

Creep Buckling Analyses of Circular Cylindrical Shells Under Axial Compression—Bifurcation Buckling Analysis by the Finite Element Method

1987 ◽  
Vol 109 (2) ◽  
pp. 179-183 ◽  
Author(s):  
N. Miyazaki
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cylindrical Shell ◽  
Axial Compression ◽  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
The Finite Element Method ◽  
Bifurcation Buckling ◽  
Creep Buckling ◽  
Circular Cylindrical Shells

The finite element method is applied to the creep buckling of circular cylindrical shells under axial compression. Not only the axisymmetric mode but also the bifurcation mode of the creep buckling are considered in the analysis. The critical time for creep buckling is defined as either the time when a slope of a displacement versus time curve becomes infinite or the time when the bifurcation buckling occurs. The creep buckling analyses are carried out for an infinitely long and axially compressed circular cylindrical shell with an axisymmetric initial imperfection and for a finitely long and axially compressed circular cylindrical shell. The numerical results are compared with available analytical ones and experimental data.

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