scholarly journals Buckling of a Short Cylindrical Shell Surrounded by an Elastic Medium

1999 ◽  
Vol 67 (1) ◽  
pp. 212-214 ◽  
Author(s):  
S. Naili ◽  
C. Oddou
Keyword(s):  
Tube Wall ◽  
Surrounding Medium ◽  
External Pressure ◽  
Elastic Tube ◽  
Geometrical Parameters ◽  
Buckling Mode ◽  
Uniform External Pressure ◽  
Cylindrical Structure ◽  
Thin Tube ◽  
Theoretical Results

The lateral surface of a cylindrical structure, which is composed of a thin tube embedded in a large outer medium, is submitted to a uniform external pressure. The buckling pressure of such a structure, corresponding to a low flexural state of the inner tube wall, is theoretically analyzed on the basis of the asymptotic method. The theoretical results are compared with experimental ones obtained from a compression test realized on an elastic tube inserted in a foam. It is found that the Euler pressure and the associated buckling mode index strongly depend upon the rheological and geometrical parameters of both the tube and the surrounding medium. [S0021-8936(00)00201-4]

Minimal liquid bridges in non-axisymmetrically buckled elastic tubes

1999 ◽  
Vol 380 ◽  
pp. 309-337 ◽  
Author(s):  
MATTHIAS HEIL
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Liquid Bridge ◽  
Tube Wall ◽  
External Pressure ◽  
Elastic Tube ◽  
Liquid Bridges ◽  
Elastic Tubes ◽  
Highly Nonlinear ◽  
Existence And Stability

This study investigates the existence and stability of static liquid bridges in non-axisymmetrically buckled elastic tubes. The liquid bridge which occludes the tube is formed by two menisci which meet the tube wall at a given contact angle along a contact line whose position is initially unknown. Geometrically nonlinear shell theory is used to describe the deformation of the linearly elastic tube wall in response to an external pressure and to the loads due to the surface tension of the liquid bridge. This highly nonlinear problem is solved numerically by finite element methods.It is found that for a large range of parameters (surface tension, contact angle and external pressure), the compressive forces generated by the liquid bridge are strong enough to hold the tube in a buckled configuration. Typical meniscus shapes in strongly collapsed tubes are shown and the stability of these configurations to quasi-steady perturbations is examined. The minimum volume of fluid required to form an occluding liquid bridge in an elastic tube is found to be substantially smaller than predicted by estimates based on previous axisymmetric models. Finally, the implications of the results for the physiological problem of airway closure are discussed.

Investigation on Snap-Through Buckling Behavior of Dished Shells Under Uniform External Pressure

2020 ◽  
Vol 87 (12) ◽  
Author(s):  
Surya Mani Tripathi ◽  
Digendranath Swain ◽  
R. Muthukumar ◽  
S. Anup
Keyword(s):  
Numerical Study ◽  
Plastic Material ◽  
External Pressure ◽  
Image Correlation ◽  
Geometrical Parameters ◽  
Imperfection Sensitivity ◽  
Value Analysis ◽  
Uniform External Pressure ◽  
Buckling Behavior ◽  
Non Linear

Abstract Previously, the buckling behavior of several conical and spherical shells have been studied with great rigor. In this paper, snap-through buckling behavior for metallic dished shells under uniform external pressure is investigated. These shells are geometrically complex since they consist of a shallow conical frustum with a flat closed top. Such shells find many engineering applications, for instance as actuator elements in control components in cryogenic engines. Currently, no clear guidelines exist for design performance evaluation of such peculiar shells. This paper aims to establish a valid FE methodology for snap-through buckling and post-buckling analysis of such shells using abaqus in tandem with experiments. A parametric study is carried out to understand the effect of geometrical parameters and imperfection sensitivity of these shells to snap-through buckling. Moreover, experiments were carried out using 3D Digital Image Correlation (3D-DIC) for measuring whole-field deflection and strains. Numerical analysis was carried out, using generalized Eigen value analysis and non-linear analysis using a modified-Riks technique with various material models to correlate with the experimental observations. Non-linear elasto-plastic analysis with a perfectly elastic-plastic material model agrees well with the experimental observations. A comparison of experimental results with that of the numerical study indicates that material plasticity has a major effect on critical buckling pressure.

Buckling Analysis of Short Cylinders of Uniform Thickness under Uniform External Pressure

2013 ◽  
Vol 351-352 ◽  
pp. 501-504
Author(s):  
Lei Chen
Keyword(s):  
External Pressure ◽  
Membrane Theory ◽  
European Standard ◽  
Membrane Stress ◽  
Buckling Mode ◽  
Critical Buckling Load ◽  
Buckling Strength ◽  
Uniform External Pressure ◽  
Cylinder Length ◽  
Buckling Stress

The failure of elastic perfect cylinders under uniform external pressure is caused by circumferential buckling. The effects of the cylinder length, of the restraining conditions at boundaries and of the length of the pressurized zone all have great influences on the critical buckling load. In the European Standard for Shells EN 1993-1-6 (2007), the critical circumferential buckling stress is obtained by introducing an external buckling factor which takes the influence of different boundary conditions into account. However, the restraint of the meridional rotation at boundaries was not considered separately for the factor. For short cylinders, any restraint of the boundaries affects the buckling mode and buckling strength greatly. In this paper, the effect of meridional end rotations on the buckling strength of short cylinders was studied. The pre-buckling membrane stress state given by membrane theory was assumed for all the analyses.

A Miniature Mobile Robot Using Piezo Vibration for Mobility in a Thin Tube

1993 ◽  
Vol 115 (2A) ◽  
pp. 270-278 ◽  
Author(s):  
Shin-ichi Aoshima ◽  
Takeshi Tsujimura ◽  
Tetsuro Yabuta
Keyword(s):  
Mobile Robot ◽  
Vibration Analysis ◽  
Tube Wall ◽  
Robot Motion ◽  
Hamilton’S Principle ◽  
Tractive Force ◽  
Hamilton's Principle ◽  
Thin Tube ◽  
Theoretical Results

This paper proposes a miniature mobile robot that uses piezo vibration to move within a thin tube. The robot consists of a piezo bimorph with elastic fins attached at an angle. Robot movement is driven by differences in the friction of the fin’s against the tube wall between the forward and backward fin movements induced by piezo vibration. After analyzing the dynamics of the piezo elements, we analyzed the robot’s mobile mechanism by extending Hamilton’s principle using the dynamic results of the piezo vibration analysis. Measurements of both mobile velocity and tractive force of an experimental robot agree closely with theoretical results. This indicates that the proposed dynamic mobile mechanism accurately expresses robot motion within a thin tube.

Elastic buckling of thin-walled polyhedral pipe liners encased in a circular pipe under uniform external pressure

2018 ◽  
Vol 123 ◽  
pp. 214-221 ◽  
Author(s):  
Zhaochao Li ◽  
Yan Tang ◽  
Fujian Tang ◽  
Yizheng Chen ◽  
Genda Chen
Keyword(s):  
External Pressure ◽  
Circular Pipe ◽  
Elastic Buckling ◽  
Uniform External Pressure ◽  
Thin Walled

scholarly journals A Method for the Statistical Evaluation of Crosstalk Effect Between Three Parallel Conductors

1999 ◽  
Vol 22 (2) ◽  
pp. 111-119
Author(s):  
P. T. Trakadas ◽  
C. N. Capsalis
Keyword(s):  
Closed Form ◽  
Uniform Distribution ◽  
Transmission Lines ◽  
Statistical Evaluation ◽  
Unit Length ◽  
Surrounding Medium ◽  
Probabilistic Approach ◽  
Random Variable ◽  
Mutual Inductance ◽  
Theoretical Results

There are several cases at which, in order to evaluate the crosstalk effect among transmission lines carrying useful signals, there is a need for probabilistic approach. This paper considers the problem of crosstalk estimation between transmission lines consisting of three conductors in a homogeneous surrounding medium, where the distance between the conductors is a random variable described by uniform distribution. The transmission lines are considered as electrically short. A closed-form equation is developed for the statistical distribution of the per-unit-length mutual inductance(lm)and an analytical one is described for the evaluation of the per-unit-length capacitance(cm). Theoretical results are compared with simulated ones for validation purposes.

Elastic-plastic collapse of 3-D damaged cylindrical shells subjected to uniform external pressure

2004 ◽  
Vol 10 (4) ◽  
pp. 343-349 ◽  
Author(s):  
X. W. Zhao ◽  
J. H. Luo ◽  
M. Zheng ◽  
H. L. Li ◽  
M. X. Lu
Keyword(s):  
Cylindrical Shells ◽  
External Pressure ◽  
Plastic Collapse ◽  
Uniform External Pressure ◽  
Elastic Plastic
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