scholarly journals Uncertainty in Loading and Control of an Active Column Critical to Buckling

2012 ◽  
Vol 19 (5) ◽  
pp. 929-937 ◽  
Author(s):  
G.C. Enss ◽  
R. Platz ◽  
H. Hanselka
Keyword(s):  
Compressive Load ◽  
Buckling Load ◽  
Buckling Mode ◽  
Design Constraint ◽  
Critical Buckling Load ◽  
Axial Compressive Load ◽  
Load Carrying ◽  
And Control ◽  
Important Design ◽  
Weight Structures

Buckling of load-carrying column structures is an important design constraint in light-weight structures as it may result in the collapse of an entire structure. When a column is loaded by an axial compressive load equal to its individual critical buckling load, a critically stable equilibrium occurs. When loaded above its critical buckling load, the passive column may buckle. If the actual loading during usage is not fully known, stability becomes highly uncertain.This paper presents an approach to control uncertainty in a slender flat column structure critical to buckling by actively stabilising the structure. The active stabilisation is based on controlling the first buckling mode by controlled counteracting lateral forces. This results in a bearable axial compressive load which can be theoretically almost three times higher than the actual critical buckling load of the considered system. Finally, the sensitivity of the presented system will be discussed for the design of an appropriate controller for stabilising the active column.

Thermal buckling analysis of double-walled carbon nanotubes considering the small-scale length effect

2011 ◽  
Vol 225 (1) ◽  
pp. 248-256 ◽  
Author(s):  
A Ghorbanpour Arani ◽  
M Mohammadimehr ◽  
A R Saidi ◽  
S Shogaei ◽  
A Arefmanesh
Keyword(s):  
Temperature Change ◽  
Buckling Analysis ◽  
Buckling Load ◽  
Small Scale ◽  
Buckling Mode ◽  
Critical Buckling Load ◽  
Winkler Model ◽  
Non Local ◽  
Double Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

In this article, the buckling analysis of a double-walled carbon nanotube (DWCNT) subjected to a uniform internal pressure in a thermal field is investigated. The effects of the temperature change, the surrounding elastic medium based on the Winkler model, and the van der Waals forces between the inner and the outer tubes are considered using the continuum cylindrical shell model. The small-length scale effect is also included in the present formulation. The results show that there is a unique buckling mode corresponding to each critical buckling load. Moreover, it is shown that the non-local critical buckling load is lower than the local critical buckling load. It is concluded that, at low temperatures, the critical buckling load for the infinitesimal buckling of a DWCNT increases as the magnitude of temperature change increases whereas at high temperatures, the critical buckling load decreases with the increasing of the temperature.

Computer Simulation of Static Buckling of Double-Layer Portal Frame

2011 ◽  
Vol 94-96 ◽  
pp. 2070-2073
Author(s):  
Zuo Yi Kang ◽  
Zhi Jun Han ◽  
Guo Yun Lu ◽  
Zhi Fang Liu
Keyword(s):  
Computer Simulation ◽  
Double Layer ◽  
Engineering Application ◽  
Buckling Load ◽  
Uniform Load ◽  
Buckling Mode ◽  
Critical Buckling Load ◽  
Portal Frame

The buckling of no-way double-layer portal frame that column is fixed is simulated by using ANSYS. Through analyzing the portal frame subjected to different loads on the roof of the structure that are uniform load, trapezoidal load and triangular load, the critical buckling load of the double-layer portal frame and buckling mode are obtained. The regular between the critical buckling load and the form of the load on the roof can be acquired by the analysis of the results, which can be used as a reference for engineering application.

Numerical Study on Buckling Behaviour of Composite Cylindrical Shells under Axial Compressive Load with Asymmetric Meshing Technique

2013 ◽  
Vol 390 ◽  
pp. 198-203 ◽  
Author(s):  
Ziaul Rehman Tahir ◽  
Parthasarathi Mandal
Keyword(s):  
Shell Model ◽  
Numerical Study ◽  
Perturbation Technique ◽  
Compressive Load ◽  
Stable State ◽  
Buckling Load ◽  
Displacement Curve ◽  
Buckling Mode ◽  
Geometric Imperfection ◽  
Post Buckling

AMT is a perturbation technique to introduce disturbance in the model without changing geometry, boundary conditions or loading conditions. Asymmetric meshing technique is employed in the form of a band along circumferential direction of the shell model. The elements size in the band is reduced as compared with the rest of shell to produce asymmetry in the meshing and four magnitudes of asymmetry in meshing are used. Asymmetric meshing affects predicted buckling load, buckling mode shape and post-buckling behaviour. The reduction in the buckling load using AMT was observed to be about 20%. An isolated dimple formed near the bifurcation point and the size of which increased to reach a stable state in the post-buckling region. The load-displacement curve behaviour applying asymmetric meshing is quite similar to the curve obtained by introducing initial geometric imperfection in the shell model.

scholarly journals Experimental and Numerical Buckling Analysis of Delaminated Hybrid Composite Beam Structures

2010 ◽  
Vol 24-25 ◽  
pp. 393-400 ◽  
Author(s):  
M.M. Nasr Esfahani ◽  
H. Ghasemnejad ◽  
P.E. Barrington
Keyword(s):  
Hybrid Composite ◽  
Laminated Composite ◽  
Composite Beams ◽  
Buckling Load ◽  
Buckling Mode ◽  
Buckling Modes ◽  
Critical Buckling Load ◽  
Finite Element Software ◽  
Numerical Studies ◽  
Laminated Composite Beams

In this paper the effect of delamination position on the critical buckling load and buckling mode of hybrid composite beams is investigated. Experimental and numerical studies are carried out to determine the buckling load of delaminated composite beams. The laminated composite beams with various laminate designs of [G90]6, [C90]8, [C0/G0]4 and [C90/G90]4 were manufactured and tested to find the critical buckling load. Three different defect positions were placed through the thickness to find three main buckling modes. It was found that delamination position and lay-up can affect the buckling mode and also the critical buckling load. By approaching the delamination position to the outer surface of the specimen the buckling load decreases. The buckling process of hybrid and non-hybrid composite beams was also simulated by finite element software ANSYS and the critical buckling loads were verified with the relevant experimental results.

Buckling and Lockup of Tubulars in Inclined Wellbores

1995 ◽  
Vol 117 (3) ◽  
pp. 208-213 ◽  
Author(s):  
J. Wu ◽  
H. C. Juvkam-Wold
Keyword(s):  
Contact Force ◽  
Inclination Angle ◽  
Compressive Load ◽  
Buckling Load ◽  
Entire Length ◽  
Frictional Drag ◽  
Axial Compressive Load ◽  
Helical Buckling

This paper studies sinusoidal and helical buckling of tubulars in inclined wellbores and the “lockup” of tubulars due to buckling. The results show that tubular buckling starts from the tubular bottom in low-inclination wellbores, where the axial compressive load is largest due to tubular weight. In high-inclination wellbores it may start from the top portion of the tubular, where the axial compressive load is largest due to frictional drag. This clarifies the confusion on whether or not the tubular buckles at once on its entire length in inclined wellbores. New sinusoidal and helical buckling load equations are presented to better predict tubular buckling in inclined wellbores (0–90 deg). The lower the wellbore inclination angle, the smaller the axial compressive load required to initiate tubular buckling. However, a certain nonzero axial compressive load is still needed to buckle the tubulars in vertical wellbores. When tubulars buckle helically, a large wall contact force will be generated, and the “slack-off” weight at the surface will not be fully transmitted to the tubular bottom due to large resultant frictional drag. The “lockup” of tubulars may even occur, where the tubular bottom load cannot be increased by slacking-off weight at the surface.

Numerical Investigation on the Buckling Failure of Slender Tubular Member with Cutout Presence

2018 ◽  
Vol 881 ◽  
pp. 122-131 ◽  
Author(s):  
Miftahul Iman ◽  
Bambang Suhendro ◽  
Henricus Priyosulistyo ◽  
Muslikh
Keyword(s):  
Nonlinear Analysis ◽  
Buckling Analysis ◽  
Buckling Load ◽  
Equilibrium Equations ◽  
Buckling Mode ◽  
Euler Formula ◽  
Critical Buckling Load ◽  
Shell Elements ◽  
Nonlinear Equilibrium ◽  
Buckling Failure

Pitting corrosion often leads to the creation of small holes in steel tubular member of platform structures when a protective coating is damaged. A single pit on slender compression element can cause a significant reduction in the buckling capacity of the member. Euler formula is no longer applicable for determining the critical buckling load when cutout presence on the member. This research was conducted to numerically study the effect of a circular hole on the buckling capacity of slender steel tubular member. A variation on hole positions was at 0.125 L, 0.25 L, 0.375 L, and 0.5 L, where L is the length of the member. The hole was taken to be 0.5 pipe diameter. Two nonlinear geometric 3D Finite Element models were developed to analyzed the member critical buckling load: (a) buckling analysis, where the problem was formulated as eigenvalue problem based on the nonlinear incremental equilibrium equations, and (b) nonlinear analysis, where the nonlinear equilibrium equations were developed and solved by several schemes to get the load – deflection curve. For the both models, the tubular member was discretized into: (a) shell elements, and (b) solid elements. The numerical results were verified by experimental investigation. The results showed that: (a) the presence of cutout reduced the buckling load significantly, (b) the reduction ranging from 3% to 10% depending on the hole positions, (c) the maximum reduction occurs when the hole position was in the middle of the member length, (d) compared to experimental results, the critical buckling load obtained from buckling analysis deviated 1~4% while those of nonlinear analysis deviated 1~5%, (e) the buckling mode corresponded with member bent away to opposite side of the cutout position.

Critical buckling load of composite laminates containing delamination using differential quadrature method and ABAQUS finite element

2021 ◽  
pp. 030932472199657
Author(s):  
Hamed Edalati ◽  
Vahid Daghigh ◽  
Kamran Nikbin
Keyword(s):  
Finite Element ◽  
Composite Laminates ◽  
Composite Laminate ◽  
Differential Quadrature Method ◽  
Compressive Load ◽  
Differential Quadrature ◽  
Buckling Load ◽  
Quadrature Method ◽  
Critical Buckling Load ◽  
Finite Element Package

Differential quadrature method (DQM) was used to compute the critical buckling load (CBL) of composite laminates containing complex delamination shapes. The composite laminate was initially flat; however, it buckled under a compressive load due to weak adhesive between the outer ply and the whole composite laminate. Previous data obtained for composite laminates containing circular or elliptical delaminations by finite element and the Rayleigh-Ritz methods as well as DQM available in the literature were used to validate the accuracy of the approach. A good agreement between the results was observed. To show the ability of this approach for calculating the CBL of a composite laminate containing complex delamination shape, a crescent-shaped delamination was considered. The CBLs for various stacking sequences of such a composite laminate were then calculated and discussed. The commercial finite element package, ABAQUS was used to validate the DQM results for crescent delamination.

Influence of axial compressive loads on buckling and free vibration response of surface-modified fly ash cenosphere/epoxy syntactic foams

2018 ◽  
Vol 52 (19) ◽  
pp. 2621-2630 ◽  
Author(s):  
Sunil Waddar ◽  
P Jeyaraj ◽  
Mrityunjay Doddamani
Keyword(s):  
Free Vibration ◽  
Natural Frequency ◽  
Testing Machine ◽  
Syntactic Foam ◽  
Compressive Load ◽  
Buckling Load ◽  
Superior Performance ◽  
Syntactic Foams ◽  
Critical Buckling Load ◽  
Compressive Loads

This work deals with experimental buckling and free vibration behavior of silane-treated cenosphere/epoxy syntactic foams subjected to axial compression. Critical buckling loads are computed from compressive load–deflection plots deduced using universal testing machine. Further, compressive loads are applied in the fixed intervals until critical loading point on different set of samples having similar filler loadings to estimate natural frequency associated with the first three transverse bending modes. Increasing filler content increases critical buckling load and natural frequency of syntactic foam composites. Increasing axial compressive load reduce structural stiffness of all the samples under investigation. Syntactic foams registered higher stiffness compared to neat epoxy for all the test loads. Similar observations are noted in case of untreated cenosphere/epoxy foam composites. Silane-modified cenosphere embedded in epoxy matrix registered superior performance (rise in critical buckling load and natural frequencies to the tune of 23.75% and 11.46%, respectively) as compared to untreated ones. Experimental results are compared with the analytical solutions that are derived based on Euler–Bernoulli hypothesis and results are found to be in good agreement. Finally, property map of buckling load as a function of density is presented by extracting values from the available literature.

scholarly journals The definition of the critical buckling load beam model and two-dimensional model of the round cylindrical shell that interact with the soil

2019 ◽  
Vol 15 (4) ◽  
pp. 291-298
Author(s):  
Sergey B. Kosytsyn ◽  
Vladimir Yu. Akulich
Keyword(s):  
Cylindrical Shell ◽  
Buckling Load ◽  
Beam Model ◽  
Equilibrium Stability ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Buckling Mode ◽  
Critical Buckling Load ◽  
Two Dimensional Model ◽  
Actual Load

Aims of research. The research is aimed at determining the critical buckling load at which the shell interacting with the soil loses equilibrium stability, and finding the buckling mode of the shell in the linear and nonlinear formulations of the task. Methods. The task is solved by a numerical method using a finite element complex, which allows investigating the stress-strain state and assessing the equilibrium stability of beam models and two-dimensional models of the round cylindrical shell. Three design cases of the beam model and two design cases of the two-dimensional model interacting with the soil are compiled. There is a load summary acting on the shell. The calculations are carried out in linear and geometrically nonlinear formulations using a linear elastic model of the material. Contact elements of one-side and two-side action are used. Critical buckling load are determined relative to the actual load of its own weight. Results. Critical buckling load are determined and the buckling mode of the round cylindrical shell interacting with the soil are found. There is a comparative analysis of the results. An assessment of the stability margin of the shell relative to the actual load is given.

Sign in / Sign up

Export Citation Format

Share Document