Buckling of Cracked Cylindrical Shells With Internal Pressure Subjected to an Axial Load

2002 ◽  
Author(s):  
A. Vaziri ◽  
H. E. Estekanchi ◽  
H. Nayeb-Hashemi
Keyword(s):  
Internal Pressure ◽  
Crack Length ◽  
Cylindrical Shells ◽  
High Stress ◽  
Pressure Vessels ◽  
Buckling Load ◽  
Critical Crack Length ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Crack Angle

Cylindrical shells constitute the main structural component in pressure vessels and pipelines. Buckling is one of the main failure considerations when designing these cylindrical shells. Defects such as cracks may develop during manufacturing or service life of these structures. These defects can severely affect their buckling behavior due to high stress field generated around these defects. Finite Element Analyses are performed to study the buckling behavior of cylindrical shells with and without a crack, under various internal pressures. Effects of crack length and its orientation on the buckling loads of cylindrical shells having a through or a thumbnail crack are studied. The results show that the buckling loads are not significantly affected for cylindrical shells with a crack less than a critical length. However, longer cracks cause local buckling of the cracked shells and can severely affect their buckling loads. This critical crack length depends on the crack orientation and the shell internal pressure. The results indicate that the buckling loads of cracked shells with internal pressure are quite sensitive to the crack angle. For cylindrical shells with an axial crack, the first buckling load drastically reduces with increasing the shell internal pressure. In contrast, the buckling load increases with the shell internal pressure for circumferentially cracked shells. The buckling loads of cracked shells with internal pressure are quite sensitive to crack angle. However, the bucking loads are little dependent to the crack angle for shells with no internal pressure.

Buckling of the Composite Cracked Cylindrical Shells Subjected to Axial Load

2003 ◽  
Author(s):  
A. Vaziri ◽  
H. Nayeb-Hashemi ◽  
H. E. Estekanchi
Keyword(s):  
Crack Length ◽  
Cylindrical Shells ◽  
Critical Length ◽  
Pressure Vessels ◽  
Buckling Load ◽  
Mode Shapes ◽  
Buckling Mode ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Composite Cylindrical Shells

Cylindrical shells constitute the main structural components in pressure vessels and pipelines. Cylindrical shells made of fiber-reinforced composites are now being considered in the design of many components due to their high specific strength and stiffness. Buckling is one of the main failure considerations, when designing the cylindrical shells. The buckling behavior of the composite cylindrical shells can severely the compromised by introducing defect in the structure, due to high stress field generated around these defects. Defects could be generated during service due to cyclic loading or during manufacturing. A reliable operation of these structures require to understand the effects of these defects on the bucking of cylindrical shells. Finite Element Analyses are performed to study the buckling behaviour of composite cylindrical shells with and without a crack, under an axial compressive loading. The effects of the plies angle on the buckling loads and buckling mode shapes of the composite cylindrical shells are studied. Furthermore, the effects of the crack length and its orientation on the buckling loads of the composite cylindrical shells are investigated. The results indicate that the global buckling loads and mode shapes of the cracked composite shells are not significantly sensitive to the presence of the defect, for shells with a crack length less than a critical length. This critical crack length depends on the crack orientation, composite ply angles, ply sequence and the cylinder geometry. For shells with a crack longer than the critical length, the buckling load reduces and the local buckling mode at the crack tip prevail the buckling behavior of the composite cylindrical shell. The optimum ply angle for attaining the maximum buckling load is specified.

On Establishing Buckling Knockdowns for Imperfection-Sensitive Shell Structures

2018 ◽  
Vol 85 (9) ◽  
Author(s):  
S. Gerasimidis ◽  
E. Virot ◽  
J. W. Hutchinson ◽  
S. M. Rubinstein
Keyword(s):  
Cylindrical Shells ◽  
Strong Dependence ◽  
Elastic Shell ◽  
External Pressure ◽  
Buckling Load ◽  
Spherical Shells ◽  
Nonlinear Buckling ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Global Buckling

This paper investigates issues that have arisen in recent efforts to revise long-standing knockdown factors for elastic shell buckling, which are widely regarded as being overly conservative for well-constructed shells. In particular, this paper focuses on cylindrical shells under axial compression with emphasis on the role of local geometric dimple imperfections and the use of lateral force probes as surrogate imperfections. Local and global buckling loads are identified and related for the two kinds of imperfections. Buckling loads are computed for four sets of relevant boundary conditions revealing a strong dependence of the global buckling load on overall end-rotation constraint when local buckling precedes global buckling. A reasonably complete picture emerges, which should be useful for informing decisions on establishing knockdown factors. Experiments are performed using a lateral probe to study the stability landscape for a cylindrical shell with overall end rotation constrained in the first set of tests and then unconstrained in the second set of tests. The nonlinear buckling behavior of spherical shells under external pressure is also examined for both types of imperfections. The buckling behavior of spherical shells is different in a number of important respects from that of the cylindrical shells, particularly regarding the interplay between local and global buckling and the post-buckling load-carrying capacity. These behavioral differences have bearing on efforts to revise buckling design rules. The present study raises questions about the perspicacity of using probe force imperfections as surrogates for geometric dimple imperfections.

Buckling Analysis of Symmetric Cross-Ply Laminated Annular Plates with Carbon Nanotubes

2014 ◽  
Vol 592-594 ◽  
pp. 901-905
Author(s):  
Pankaj Kumar ◽  
Pandey Ramesh
Keyword(s):  
Carbon Nanotubes ◽  
Boundary Condition ◽  
Carbon Nanotube ◽  
Aspect Ratio ◽  
Energy Method ◽  
Buckling Analysis ◽  
Buckling Load ◽  
Buckling Loads ◽  
Annular Plates ◽  
Buckling Behavior

The Paper presents the buckling response of composite annular plates with under uniform internal and external radial edge loads using energy method. For the equation of stability Trefftez rule is used. The paper consists of buckling behavior of laminate (90/0) s, influence of some parameters such as thickness, boundary condition, aspect ratio on buckling loads and modes are investigated. Present results are compared with other papers. In this paper the effect of % weight of carbon nanotube (MWCNT) on the buckling load is also investigated.

The effects of cutouts on buckling behavior of composite plates

2012 ◽  
Vol 19 (3) ◽  
pp. 323-330 ◽  
Author(s):  
Ahmet Erkliğ ◽  
Eyüp Yeter
Keyword(s):  
Fiber Orientation ◽  
Polymer Matrix Composites ◽  
Orientation Angle ◽  
Composite Plates ◽  
Buckling Load ◽  
Matrix Composites ◽  
Element Analysis ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Fiber Orientation Angle

AbstractCutouts such as circular, rectangular, square, elliptical, and triangular shapes are generally used in composite plates as access ports for mechanical and electrical systems, for damage inspection, to serve as doors and windows, and sometimes to reduce the overall weight of the structure. This paper addresses the effects of different cutouts on the buckling behavior of plates made of polymer matrix composites. To study the effects of cutouts on buckling, loaded edges are taken as fixed and unloaded edges are taken as free. Finite element analysis is also performed to predict the effects of different geometrical cutouts, orientations, and position of cutouts on the buckling behavior. The results show that fiber orientation angle and cutout sizes are the most important parameters on the buckling loads. For all types of cutouts the buckling loads decrease dramatically by increasing the fiber orientation angle. It is observed that minimum buckling load is reached when 45° fiber angle is used, and after this angle critical buckling load begins to increase. Also, it is concluded that while fiber orientation angle is 0°, elliptical cutout has the highest buckling load and while fiber orientation angle is 45°, circular cutout has the highest buckling load.

An Experiential Optimization Design Method for Orthogonal Rib-Stiffened Thin Walled Cylindrical Shells under Axial Loading

2011 ◽  
Vol 110-116 ◽  
pp. 1773-1783
Author(s):  
Jia Mao ◽  
Yu Feng Chen ◽  
Wei Hua Zhang
Keyword(s):  
Optimization Design ◽  
Design Method ◽  
Mass Parameter ◽  
Cylindrical Shells ◽  
Reference Value ◽  
Buckling Load ◽  
Element Analysis ◽  
Buckling Loads ◽  
Load Optimization ◽  
Thin Walled

Parametric structural FEA (Finite Element Analysis) models of the orthogonal rib-stiffened thin walled cylindrical shells are established using APDL (ANSYS Parametric Design Language). An experiential optimization design method is then developed based on conclusions of series numerical analysis investigating the effects of parameters’ modification upon buckling loads and modes of the structure. The effects of single design parameter modification under both variational and fixed volume (mass) constraints upon the buckling loads and modes indicate that, only one design scheme is able to obtain maximum buckling load when deployment of the strengthening ribs and volume (mass) parameter were settled previously, and minimum mass would be obtained while this maximum buckling load equals to the required design load. Optimization calculations for aluminum alloy material and layered C/E (Carbon/Epoxy) composite material shells with three layering styles are implemented and discussed, and some useful conclusions are obtained. Method and approach developed in this paper provide certain reference value for the optimal design of such structures.

Nonlinear Buckling Behavior of Cylindrical Shells of Uniform Thickness under Wind Load

2012 ◽  
Vol 594-597 ◽  
pp. 2753-2756
Author(s):  
Lei Chen ◽  
Yi Liang Peng ◽  
Li Wan ◽  
Hong Bo Li
Keyword(s):  
Cylindrical Shells ◽  
External Pressure ◽  
Pressure Vessels ◽  
Wind Pressure ◽  
Uniform Thickness ◽  
Nonlinear Buckling ◽  
Buckling Modes ◽  
Uniform External Pressure ◽  
Aspect Ratios ◽  
Buckling Behavior

Abstract: Cylindrical shells are widely used in civil engineering. Examples include cooling towers, nuclear containment vessels, metal silos and tanks for storage of bulk solids and liquids, and pressure vessels. Cylindrical shells subjected to non-uniform wind pressure display different buckling behaviours from those of cylinders under uniform external pressure. At different aspect ratios, quite complex buckling modes occur. The geometric nonlinearity may have a significant effect on the buckling behavior. This paper presents a widely study of the nonlinear buckling behavior of cylindrical shells of uniform thickness under wind loading. The finite element analyses indicate that for stocky cylinders, the nonlinear buckling modes are the circumferential compression buckling mode, which is similar to cylinders under uniform external pressure, while for cylinders in mediate length, pre-buckling ovalization of the cross-section has an important influence on the buckling strength.

scholarly journals Nonlinear Buckling of Fixed Functionally Graded Material Arches Under a Locally Uniformly Distributed Radial Load

2021 ◽  
Vol 8 ◽  
Author(s):  
Hanwen Lu ◽  
Jinman Zhou ◽  
Zhicheng Yang ◽  
Airong Liu ◽  
Jian Zhu
Keyword(s):  
Limit Point ◽  
Functionally Graded ◽  
Buckling Load ◽  
Equilibrium Path ◽  
Radial Load ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Bifurcation Buckling ◽  
Nonlinear Equilibrium ◽  
Graded Material

Functionally graded material (FGM) arches may be subjected to a locally radial load and have different material distributions leading to different nonlinear in-plane buckling behavior. Little studies is presented about effects of the type of material distributions on the nonlinear in-plane buckling of FGM arches under a locally radial load in the literature insofar. This paper focuses on investigating the nonlinear in-plane buckling behavior of fixed FGM arches under a locally uniformly distributed radial load and incorporating effects of the type of material distributions. New theoretical solutions for the limit point buckling load and bifurcation buckling loads and nonlinear equilibrium path of the fixed FGM arches under a locally uniformly distributed radial load that are subjected to three different types of material distributions are derived. The comparisons between theoretical and ANSYS results indicate that the theoretical solutions are accurate. In addition, the critical modified geometric slendernesses of FGM arches related to the switches of buckling modes are also derived. It is found that the type of material distributions of the fixed FGM arches affects the limit point buckling loads and bifurcation buckling loads as well as the nonlinear equilibrium path significantly. It is also found that the limit point buckling load and bifurcation buckling load increase with an increase of the modified geometric slenderness, the localized parameter and the proportional coefficient of homogeneous ceramic layer as well as a decrease of the power-law index p of material distributions of the FGM arches.

Buckling of fiber metal laminated plates – numerical and experimental studies

2020 ◽  
Vol 92 (3) ◽  
pp. 472-481
Author(s):  
Elluri Venkata Prasad ◽  
Shishir Kumar Sahu
Keyword(s):  
Aspect Ratio ◽  
Boundary Conditions ◽  
Thickness Ratio ◽  
Buckling Load ◽  
Element Formulation ◽  
Buckling Loads ◽  
Content Type ◽  
Buckling Behavior ◽  
Fiber Metal ◽  
Ply Orientation

Purpose The purpose of this study is to study the buckling behavior of new aircraft material, i.e. glass fiber metal laminated (GFML) plates. Design/methodology/approach The first-order Reissner–Mindlin theory is used in the present finite element formulation to determine the buckling loads of GFML plates. A program is developed in MATLAB for analyzing the effect of different parameters on buckling loads GFML plates. A set of experiments was performed to determine critical buckling loads of GFML plates using universal testing machine INSTRON 8862 and compared with predictions using the numerical model. Findings The effects of various parameters such as aspect ratio, side to thickness ratio, ply orientation and boundary conditions on buckling loads of GFMLs are examined. With the increase of aspect ratio, the reduction in buckling load is observed, while the increase inside to thickness ratio decreases the buckling load of GFML plates. There is a slight variation in buckling load with the increase of ply orientation. The buckling load is significantly influenced by boundary conditions because of restraint at the edges. Practical implications These types of materials are used in lightweight structures such as aircraft, aerospace and military vehicles. The results reported in the present study can be used as design guidelines while designing fiber metal laminated (FML) plated structures. Originality/value For the first time, the authors have studied the buckling behavior of bidirectional woven FML plates using both numerical and experimental techniques.

PROBABILISTIC DESIGN OF AXIALLY COMPRESSED COMPOSITE CYLINDERS WITH GEOMETRIC AND LOADING IMPERFECTIONS

2010 ◽  
Vol 10 (04) ◽  
pp. 623-644 ◽  
Author(s):  
BENEDIKT KRIEGESMANN ◽  
RAIMUND ROLFES ◽  
CHRISTIAN HÜHNE ◽  
JAN TEßMER ◽  
JOHANN ARBOCZ
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Fourier Coefficients ◽  
Cylindrical Shells ◽  
Probabilistic Approach ◽  
Element Model ◽  
Buckling Load ◽  
Probabilistic Design ◽  
Composite Shells ◽  
Buckling Loads

The discrepancy between the analytically determined buckling load of perfect cylindrical shells and experimental test results is traced back to imperfections. The most frequently used guideline for design of cylindrical shells, NASA SP-8007, proposes a deterministic calculation of a knockdown factor with respect to the ratio of radius and wall thickness, which turned out to be very conservative in numerous cases and which is not intended for composite shells. In order to determine a lower bound for the buckling load of an arbitrary type of shell, probabilistic design methods have been developed. Measured imperfection patterns are described using double Fourier series, whereas the Fourier coefficients characterize the scattering of geometry. In this paper, probabilistic analyses of buckling loads are performed regarding Fourier coefficients as random variables. A nonlinear finite element model is used to determine buckling loads, and Monte Carlo simulations are executed. The probabilistic approach is used for a set of six similarly manufactured composite shells. The results indicate that not only geometric but also nontraditional imperfections like loading imperfections have to be considered for obtaining a reliable lower limit of the buckling load. Finally, further Monte Carlo simulations are executed including traditional as well as loading imperfections, and lower bounds of buckling loads are obtained, which are less conservative than NASA SP-8007.

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