scholarly journals A Parametric Study of the Effect of Geometric Imperfections on the Buckling Behaviour of Composite Laminated Cylinders

2002 ◽  
Vol 11 (3) ◽  
pp. 096369350201100 ◽  
Author(s):  
A.S. Petreli ◽  
N.G. Tsouvalis
Keyword(s):  
Parametric Study ◽  
Fe Method ◽  
Geometric Imperfections ◽  
Buckling Strength ◽  
Initial Imperfections ◽  
Hydrostatic Load

This paper presents the results of a parametric study about the type and magnitude of initial imperfections on the buckling behaviour of composite laminated cylinders under external hydrostatic load. Using the FE method, cylinders with two particular types of initial imperfections are non-linearly analysed. Results show that significant improvement of the cylinder buckling strength is observed when initial imperfections have a selected shape and magnitude, which induces a final cylinder deflected shape different from the modeshape of the geometrically perfect cylinder.

Numerical Study about Combined Effect of Distributed Initial Imperfections and Dent on Ultimate Strength of Square Plates under Uni-Axial Compression

2015 ◽  
Vol 813-814 ◽  
pp. 1037-1041 ◽  
Author(s):  
Duraikannou Peroumal ◽  
E. Sidhuvilaji ◽  
B. Prabu ◽  
A.V. Raviprakash
Keyword(s):  
Ultimate Strength ◽  
Axial Compression ◽  
Thick Plate ◽  
Numerical Study ◽  
Combined Effect ◽  
Geometric Imperfections ◽  
Buckling Strength ◽  
Initial Imperfections ◽  
Numerical Result ◽  
Local Dent

Aim of this present work is to study the combined effect of distributed geometric global imperfection and a local dent on buckling strength of thin square plates subjected to uni-axial compression. Steady state non linear FE analysis including both material and geometrical non linearities is used to determine the ultimate strength of the dented plates. From the numerical result it is found that in case of low thickness plates global geometric imperfections effect is more dominant and in case of thick plate dent effect is found to be more dominant.

Buckling Strength of Pressurized Cylindrical Shells under Axial Compression

2014 ◽  
Vol 638-640 ◽  
pp. 1750-1753
Author(s):  
Yu Chao Zheng ◽  
Yang Yan ◽  
Pei Jun Wang
Keyword(s):  
Numerical Simulation ◽  
Internal Pressure ◽  
Axial Compression ◽  
Parametric Study ◽  
Shell Thickness ◽  
Steel Shell ◽  
Plastic Buckling ◽  
Buckling Strength ◽  
Elastic Plastic ◽  
Steel Strength

A systematic parametric study was carried out to investigate the elastic and elastic-plastic buckling behaviors of imperfect steel shell subject to axial compression and internal pressure. Studied parameters include the magnitude of internal pressure, steel strength, and ratio of cylinder radius to shell thickness. Design equations were proposed for calculating the elastic and elastic-plastic buckling strength of imperfect steel shells under combination of axial compression and internal pressure. The buckling strength predicated by proposed equations agrees well with that from the numerical simulation.

Comparison of Numerical Results With Experiments on the Ultimate Strength of Long Stiffened Panels

2011 ◽  
Author(s):  
Mingcai Xu ◽  
C. Guedes Soares
Keyword(s):  
Numerical Analysis ◽  
Test Results ◽  
Buckling Mode ◽  
Geometric Imperfections ◽  
Geometric Nonlinearities ◽  
Stiffened Panels ◽  
Initial Imperfections ◽  
Linear Buckling ◽  
Initial Geometric Imperfections ◽  
Collapse Behavior

The behavior of long stiffened panels are simulated numerically and compared with test results of axial compression until collapse, to investigate the influence of the stiffener’s geometry. The material and geometric nonlinearities are considered in the simulation. The initial geometric imperfections, which affect the collapse behavior of stiffened panels, are also analyzed. The initial imperfections are assumed to have the shape of the linear buckling mode. Four types of stiffeners are made of mild or high tensile steel for bar stiffeners and mild steel for ‘L’ and ‘U’ stiffeners. To produce adequate boundary conditions at the loaded edges, three bays stiffened panels were used in the tests and in the numerical analysis.

On the Choice of Initial Geometric Imperfections in Externally Pressurized Shells

1999 ◽  
Vol 121 (1) ◽  
pp. 71-76 ◽  
Author(s):  
J. Błachut ◽  
O. R. Jaiswal
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Carrying Capacity ◽  
Circular Cross Section ◽  
Load Carrying Capacity ◽  
Geometric Imperfections ◽  
Elliptical Cross ◽  
Buckling Strength ◽  
Load Carrying ◽  
Initial Geometric Imperfections

Localized and global, of eigenmode type, initial geometric imperfections were superimposed on perfect torispherical, ellipsoidal, and toroidal shells of circular and elliptical cross section. Reduction of the load-carrying capacity was then calculated numerically for various geometries and the yield point of material which was assumed to be mild steel. Results show that the buckling strength of torispheres and ellipsoids could be strongly affected by imperfections, but reduction of its magnitude was dependent on the choice of imperfection shape and, more importantly, on the imperfection’s location. Calculations carried out for closed toroids of circular cross section show that these shells are not sensitive to eigenmode-type imperfections, while toroids with elliptical cross sections are sensitive to eigen-imperfections.

Design of built-up steel beam-columns composed of two-channel sections

2020 ◽  
Author(s):  
George Iskander ◽  
Emam Soliman ◽  
Ezzeldin Yazeed Sayed-Ahmed
Keyword(s):  
Experimental Investigation ◽  
Numerical Model ◽  
Experimental Work ◽  
Parametric Study ◽  
Design Method ◽  
Steel Beam ◽  
Fe Model ◽  
Beam Columns ◽  
Initial Imperfections ◽  
Good Agreement

Built-up columns composed of two chords present an ideal design for long columns subject to high straining actions. The objective of this paper is to investigate the capacity of built-up columns composed of two-channel sections subjected to eccentric loading and propose a design method for them. A nonlinear numerical FE model is developed for these columns and verified against experimental investigation available from literature; the model includes both the geometric and materials nonlinearities along with the effect of initial imperfections. The model is used to perform a parametric study to investigate the effect of different factors on the built-up columns’ capacity. The results of the parametric study are also used to propose a design method for these columns. A limited experimental investigation is performed on two eccentrically loaded built-up columns, the results of experimental work showed good agreement with the numerical model results and the proposed design method.

Effects of Initial Geometric Imperfections on the Stability of Steel-Concrete Composite Ribbed Shell

2011 ◽  
Vol 243-249 ◽  
pp. 7001-7004 ◽  
Author(s):  
Ling Ling Wang ◽  
Yu Zhen Chang
Keyword(s):  
Critical Load ◽  
Single Layer ◽  
Displacement Curve ◽  
Element Analysis ◽  
Geometric Imperfections ◽  
Initial Imperfections ◽  
Mode Method ◽  
Ribbed Shell ◽  
Instability Regions ◽  
Initial Geometric Imperfections

The paper proposed a new system of spatial structure: steel- concrete composite ribbed shell, and briefly compared the three analysis methods considering the initial imperfections of structures: the random imperfection mode method, the consistent imperfection mode method and the improved random imperfection mode method. By using of the consistent imperfection mode method and nonlinear finite element analysis software ANSYS, we analyzed a composite steel-concrete ribbed shell with the span of 40m and span ratio f/L=1/4, which is simply supported at its surrounding and is subjected to uniform loading along it’s whole span. The critical load and instability regions of this shell are presented. The results show that with the increasing of the initial imperfections, the value of critical load decreased from 27% to 36%; the trend of load-displacement curve and the location of structural instability regions remain unchanged, only the shape of instability regions will change. This indicted that the effect of the initial imperfections within composite ribbed shell is far less than its influence to the single-layer shell. The steel-concrete composed ribbed shell is not sensitive to the initial geometric imperfections and shows a strong post-buckling performance.

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