Influence of geometrical parameters on the stress state of longitudinally corrugated elliptic cylindrical shells

2009 ◽  
Vol 45 (2) ◽  
pp. 187-192 ◽  
Author(s):  
Ya. M. Grigorenko ◽  
A. Ya. Grigorenko ◽  
L. I. Zakhairichenko
Keyword(s):  
Stress State ◽  
Cylindrical Shells ◽  
Geometrical Parameters

scholarly journals Prediction of Vibrational Behavior of Grid-Stiffened Cylindrical Shells

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
G. H. Rahimi ◽  
M. Hemmatnezhad ◽  
R. Ansari
Keyword(s):  
Shell Theory ◽  
Cylindrical Shells ◽  
Element Model ◽  
Geometrical Parameters ◽  
Equivalent Stiffness ◽  
Theoretical Formulation ◽  
Vibrational Behavior ◽  
Thin Shell Theory ◽  
Stiffened Cylindrical Shells ◽  
Good Agreement

A unified analytical approach is applied to investigate the vibrational behavior of grid-stiffened cylindrical shells with different boundary conditions. A smeared method is employed to superimpose the stiffness contribution of the stiffeners with those of shell in order to obtain the equivalent stiffness parameters of the whole panel. Theoretical formulation is established based on Sanders’ thin shell theory. The modal forms are assumed to have the axial dependency in the form of Fourier series whose derivatives are legitimized using Stoke's transformation. A 3D finite element model is also built using ABAQUS software which takes into consideration the exact geometric configuration of the stiffeners and the shell. The achievements from the two types of analyses are compared with each other and good agreement has been obtained. The Influences of variations in shell geometrical parameters, boundary condition, and changes in the cross stiffeners angle on the natural frequencies are studied. The results obtained are novel and can be used as a benchmark for further studies. The simplicity and the capability of the present method are also discussed.

Finite Element Modeling of Steel Pipeline Reconstruction Using Fiberglass Composite Material

2015 ◽  
Vol 725-726 ◽  
pp. 648-653 ◽  
Author(s):  
Ekaterina A. Nekliudova ◽  
Artem S. Semenov ◽  
S.G. Semenov ◽  
Boris E. Melnikov
Keyword(s):  
Finite Element ◽  
Composite Material ◽  
Stress State ◽  
Elastic Moduli ◽  
Strength Properties ◽  
Geometrical Parameters ◽  
Effective Elastic Moduli ◽  
Composite Part ◽  
Steel Pipeline ◽  
Fiberglass Composite

A stress state of the partially damaged underground steel pipeline after reconstruction by means of the fiberglass composite material is considered. The strength properties of the composite are determined experimentally. The effective elastic moduli of the composite are determined by means of the finite element homogenization. Tsai-Wu failure criterion is used for the composite part of the pipeline. The influence of geometrical parameters and loading conditions on the safety factor of the pipeline is analyzed and discussed.

Buckling of Thin Cylindrical Shells Under Locally Elevated Compressive Stresses

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
J. Michael Rotter ◽  
Minjie Cai ◽  
J. Mark F. G. Holst
Keyword(s):  
Stress State ◽  
Cylindrical Shells ◽  
Peak Stress ◽  
Theoretical Research ◽  
Design Rule ◽  
Uniform Stress ◽  
Geometric Imperfection ◽  
Buckling Strength ◽  
Shell Buckling ◽  
Compressive Stresses

Thin cylindrical shells used in engineering applications are often susceptible to failure by elastic buckling. Most experimental and theoretical research on shell buckling relates only to simple and relatively uniform stress states, but many practical load cases involve stresses that vary significantly throughout the structure. The buckling strength of an imperfect shell under relatively uniform compressive stresses is often much lower than that under locally high stresses, so the lack of information and the need for conservatism have led standards and guides to indicate that the designer should use the buckling stress for a uniform stress state even when the peak stress is rather local. However, this concept leads to the use of much thicker walls than is necessary to resist buckling, so many knowledgeable designers use very simple ideas to produce safe but unverified designs. Unfortunately, very few scientific studies of shell buckling under locally elevated compressive stresses have ever been undertaken. The most critical case is that of the cylinder in which locally high axial compressive stresses develop extending over an area that may be comparable with the characteristic size of a buckle. This paper explores the buckling strength of an elastic cylinder in which a locally high axial membrane stress state is produced far from the boundaries (which can elevate the buckling strength further) and adjacent to a serious geometric imperfection. Care is taken to ensure that the stress state is as simple as possible, with local bending and the effects of internal pressurization eliminated. The study includes explorations of different geometries, different localizations of the loading, and different imperfection amplitudes. The results show an interesting distinction between narrower and wider zones of elevated stresses. The study is a necessary precursor to the development of a complete design rule for shell buckling strength under conditions of locally varying axial compressive stress.

BUCKLING AND POSTBUCKLING ANALYSIS OF LAMINATED CYLINDRICAL SHELLS USING THE THIRD-ORDER SHEAR DEFORMATION THEORY

2004 ◽  
Vol 04 (03) ◽  
pp. 293-312 ◽  
Author(s):  
R. A. ARCINIEGA ◽  
P. B. GONÇALVES ◽  
J. N. REDDY
Keyword(s):  
Shear Deformation ◽  
Cylindrical Shells ◽  
Ritz Method ◽  
Shear Deformation Theory ◽  
Physical Parameters ◽  
Geometrical Parameters ◽  
Postbuckling Behavior ◽  
Equilibrium Equations ◽  
Postcritical Behavior ◽  
Laminated Cylindrical Shells

In the present work the buckling and postbuckling behavior of laminated cylindrical shells under axial compression and lateral pressure loading are investigated. A nonlinear theory for thin cylinders incorporating the effects of transverse shear deformation is employed. A modal solution based on the Koiter theory is utilized to derive the nonlinear equilibrium equations for the postcritical behavior of the shell. The Rayleigh–Ritz method is used to obtain analytical solutions for the critical load through algebraic routines written in Maple. Prebuckling and postbuckling equations are also solved by using symbolic computation. The influence played by geometrical parameters of the cylinder and physical parameters of the laminate (i.e. fiber orientation of each lamina, material properties and number of layers) on the critical and postcritical behavior of the shell is examined. It is noticed that the stability 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.

Dynamic Stability Analysis of Cans in Reactor Coolant Pump Subjected to Axial Flow

2014 ◽  
Author(s):  
Wenbo Ning ◽  
Dezhong Wang
Keyword(s):  
Dynamic Stability ◽  
Cylindrical Shells ◽  
Axial Flow ◽  
Geometrical Parameters ◽  
Coolant Pump ◽  
Critical Flow Velocity ◽  
Reactor Coolant ◽  
Annular Gap ◽  
The Stability ◽  
Canned Motor

The stator and rotor cans in canned motor reactor coolant pump are assumed to be elastic coaxial cylindrical shells due to their particular geometric structures in present study. Thin shell structures such as cans are prone to buckling instabilities. Furthermore, a lot of accidents were caused by losing stability. The dynamic behavior of coaxial circular cylindrical shells subjected to axial fluid flow in the annular gap between two shells is investigated in this paper. The outer shell is stiffened by ring-ribs because of its instability easily. The shell is modeled based on Donnell’s shallow theory. The “smeared stiffeners” approach is used for ring-stiffeners. The fluid is assumed to be an incompressible ideal fluid and the potential flow theory is employed to describe shell-fluid interaction. Numerical analyses are conducted by means of energy variation to obtain the critical flow velocity of losing stability with aid of Hamilton principle. This study shows effects of geometrical parameters on stability of shells. The size and number of ring-stiffeners on dynamic stability are examined. It is found that stiffeners can vary modes instability and enhance the stability of shells. The flow velocities of losing stability with different boundary conductions can be calculated and compared. The results show clamped shells are more stable than simply supported shells. The results presented are in reasonable agreement with those available in the literature.

Nonlinear Thermo-Mechanical Stability Analysis of Eccentrically Spiral Stiffened Sandwich Functionally Graded Cylindrical Shells Subjected to External Pressure

2019 ◽  
Vol 11 (05) ◽  
pp. 1950045 ◽  
Author(s):  
Vu Hoai Nam ◽  
Nguyen Thi Phuong ◽  
Cao Van Doan ◽  
Nguyen Thoi Trung
Keyword(s):  
Mechanical Stability ◽  
Thermal Environment ◽  
Cylindrical Shells ◽  
Geometrical Nonlinearity ◽  
External Pressure ◽  
Functionally Graded ◽  
Geometrical Parameters ◽  
Nonlinear Buckling ◽  
Circular Cylindrical Shells ◽  
The Galerkin Method

A new analytical approach to investigate the nonlinear buckling and postbuckling of the sandwich functionally graded circular cylindrical shells reinforced by ring and stringer or spiral stiffeners subjected to external pressure is presented in this paper. By employing the Donnell shell theory, the geometrical nonlinearity in Von Kármán sense and developed Lekhnitskii’s smeared stiffener technique, the governing equations of sandwich functionally graded circular cylindrical shells are derived. Resulting equations are solved by applying the Galerkin method to obtain the explicit expression of critical buckling external pressure load and postbuckling load–deflection curve. Effects of spiral stiffeners, thermal environment, external pressure, and geometrical parameters on nonlinear buckling behavior of sandwich functionally graded circular cylindrical shells are shown in numerical results.

Deformation and stability of technologically imperfect cylindrical shells in a nonuniform stress state

1990 ◽  
Vol 22 (12) ◽  
pp. 1745-1750 ◽  
Author(s):  
V. I. Mossakovskii ◽  
A. M. Mil'tsyn ◽  
V. I. Olevskii
Keyword(s):  
Stress State ◽  
Cylindrical Shells ◽  
Nonuniform Stress
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