Talk:Buckling

message: I have added a point to help emphasise the importance of boundary conditions, so hopefully readers will appreciate that it is of critical importance to correctly judge the boundary conditions of a real life structure if they hope to achieve any accuracy in their structural analysis. I also added a picture of mine which I think illustrates this clearly Grahams Child 08:48, 25 May 2006 (UTC)
thread_title: Emphasised the role of boundary conditions

message: This needs a picture desperately.  Also, the introduction could be a little less technical.  Anyone up to the challenge?--Joel 18:18, 18 May 2005 (UTC)
thread_title: Picture Required

message: Comment on the following excerpt:
 "If the load on a column is applied through the center of gravity of its cross section 
 it is called an axial load."
I am aware that "center of gravity" --U.S. spelling--is commonly used interchangeably with "centroid of cross section."  People may understand the intent given the context of the discussion, but, considering that this is an encyclopedia, it seems that the technically correct term should be used.  The need for this change is possibly made more urgent by the article on "center of gravity," which makes no mention of the misnomer.
To be clear, the centroid is the geometric center of an area (for buckling, we are interested in centroids of areas).  The article on "centroid" seems quite good so no need to reproduce it here.  Centroids do not require a knowledge of the volume or the density distribution in the column, nor of the gravitational field in which the column resides.  Perhaps if the buckling article discussed the buckling of columns under their own weight, then these other terms would be relevant.
The center of gravity on the other hand, while a mathematically similar concept, does involve the length of the beam, the density distribution, and the variation of the gravitational field.  It, however, does not generally have any relationship to the issue of buckling.
So here is a proposed improvement to the above quote:
  "If the load on a column is applied along its centroidal axis it is called an axial load."
Would this change add value to the article?
On a related note, I have long wondered how "moment of inertia" became synonymous with both "second moment of mass" and "second moment of area."  The "moment of interia" article does identify usage of "moment of inetia" for the the latter term as a misnomer.  So given the widespread use of the phrase "area moment of inertia," would it still be helpful to replace it with the (perhaps less familiar) more technically sound "second moment of area?"  That article is quite good also.
AJOS 22:19, 19 March 2006 (UTC)
thread_title:  Center of Gravity vs. Centroid; Moment of Inertia vs. Second Moment of Area 

message: In the article it is stated: "Examination of this formula [the Euler load] reveals the following interesting facts with regard to the load bearing ability of columns: that elasticity and not compressive strength of the materials of the column determines the critical load."
On this backgriound I am wondering why in Codes of Practice such as BS 5950 the load-carrying capacity of members in compression is dependent on material strength and not Young's modulus? The article does hint at a number of possible reasons ("a number of empirical column formulae have been developed to agree with test data" and "buckling will generally occur slightly before the theoretical buckling strength of a structure due to plasticity of the material"), but it would benefit the article to devote an entire section to this question. Does anyone know the answer? Is it already in the article? --Ahnielsen 21:11, 26 June 2006 (UTC)
replies: text: I have replied on your talk page Alangstone 22:55, 26 June 2006 (UTC)
thread_title:  Design of members in compression 

message: I don't want to start a revert war here, so I will explain why I am changing the opening paragraph back to the prior edit.  
1) a member that fails as a result of buckling will fail at a lower load than the ultimate compressive strength of the material.  It is _not_ possible for the member to carry a load above the ultimate compressive strength, as it would have failed in direct compression once the load reached ultimate. I tried to disambiguate this by adding the word "ultimate" into the opening sentence.
2) I have removed the sentence that read "If the actual compressive stresses were lower, it would not exceed the design requirements."  This statement is not accurate.  Just because a column is subjected to a load below critical for buckling, it does not necessarily mean that the member meets design requirements - there are other possible failure modes that must be considered which can occur well below the buckling load.  (ex - Connection failure)
Alangstone 03:16, 9 August 2006 (UTC)
thread_title:  First paragraph 

message: Happened across this page while looking for information on buckling of curved columns...  While I'm sure Mr. Roland's neck is quite long and slender, and his head is sufficiently massive as to cause buckling in Earth's gravitational field, I'm not sure that this information is encyclopedic.  I removed the link to the non-existant article.--156.68.7.124 15:21, 4 October 2006 (UTC)
thread_title:  Doug Roland's Neck 

message: Euler's theory merely determines the conditions for stability under load.  Below a certain load, the tendency is for the deflection in response to any (lateral) perturbation is to return to zero. Above the critical load deflection will keep on increasing until catastrophic failure occurs.  As with all ideas on stability, some infinitesmal displacement is implicitly assumed.   Perfection in alignment, straightness and homogeneity of material is unfortunately beyond us mere mortals. Real life engineers do not have access to the mathematican's stock of inextensible strings, massless pulleys, frictionless pegs, etc..Gordon Vigurs 06:55, 10 April 2007 (UTC)
thread_title: Comment on Axial vs. Eccentric loading conditions 

message: If you are saying, in section Buckling in columns, that K=2 for hinged bar than your equation for stress is correct. Equation for surface moment of inertia is not correct. That is, the second equation is for the polar moment of inertia and that is not the one used here.
I_y=I_x=\frac{1}{2} A R^2
I\neq A R^2
Marko Raodosavljevic152.88.80.79 09:53, 25 May 2007 (UTC)
thread_title:  The second order surface moment of inertia... 

message: Not only is the following section quite clearly copy and pasted from somewhere else, assumadly a lecturers notes, but it has been done so extremely lazily:
"When a beam is loaded in flexure, the compression side is in compression, and the tension side is in tension. If the beam is not supported in the lateral direction (i.e., perpendicular to the plane of bending), and the flexural load increases to a critical limit, the beam will fail due to lateral buckling of the compression flange. In wide-flange sections, if the compression flange buckles laterally, the cross section will also twist in torsion, resulting in a failure mode known as lateral-torsional buckling.
Any problems with this come and see davie boyce in room 801"
Removal of the bottom line will not change the fact that it has been copied, the section will need rewriting completely.Pledger166 (talk) 23:58, 10 January 2008 (UTC)
thread_title:  LTB section 

message: I wish to know if there is any link with that notion? 216.86.113.233 (talk) 07:49, 6 July 2008 (UTC)
replies: text: Yes there is, for example if a lateral load is applied to the top of a column it may cause some horisontal deflection e at the top of the column. Any vertical forces  F applied at the head of the column would then create a moment Fe which has a major influence on the buckling capacity of the column.Gregorydavid (talk) 08:27, 6 July 2008 (UTC)
thread_title:  any link to [[Deflection (engineering)]]? 

message: This 
For one end fixed and the other end pinned, K = 1.0/√2.0.
is wrong!! I dont have a book to look for the correct value, but I remember a discussion in german wikipedia just about this! --130.83.237.45 (talk) 08:16, 18 March 2009 (UTC)
thread_title:  Wrong value!! 

message: I have a book on this, but currently I don't have much time. SongJie@NTU (talk) 14:26, 19 April 2009 (UTC)
thread_title:  Topics on shell and/or plate buckling should be included 

message: The article currently reads in the first paragraph:
[...] where the actual compressive stress at the point of failure is more than the ultimate compressive stresses that the material is capable of withstanding. [...]
I believe this statement is incorrect. To be made correct "more" should be replace by "less".
I offer the following explanation:
Consider a long beam L and a short beam S. Both have the same cross-section A. The cross-section shapes are the same as well. Both L and S are axially loaded with the same force F, so both develop the same "actual compressive stress": sigma=F/A. Beam L is longer than S, so it is more likely to fail by buckling than S. Let us assume that F is low enough that the "actual compressive stress" in L (and therefore in S) does not exceed the compressive yield stress. Let us further assume that S does not buckle and L does, which according to the Euler equation is quite possible (just make L long enough). In that situation the "actual compressive stress" is LESS (not more) than "the material is capable of withstanding" (i.e. the compressive yield stress) or else both S and L would have failed.Paulcbrand (talk) 16:37, 13 May 2010 (UTC)
replies: text: I had reverted it to what appears to be the long-standing wording.  Whatever the proper definition, it needs to be made far clearer to avoid continued confusion. --Ronz (talk) 16:41, 13 May 2010 (UTC)
replies: text: Perhaps the following can serve as an addition explanation: if buckling would occur when the compressive stress at the point of failure is MORE than the ultimate compressive stresses that the material is capable of withstanding then removing the buckling force would not restore the beam to its original shape, because plastic deformation would have taken place. In Eulerian buckling a beam is restored to its original shape when the force is removed (like for the beams in the laboratory picture showing the four buckling modes). Hence at no time during buckling was the yield stress exceeded. Eulerian buckling is an inherently elastic phenomenon (albeit an instable one).Paulcbrand (talk) 17:01, 13 May 2010 (UTC)
replies: text:  I agree with Paulcbrand.  The long-standing wording was incorrect.Bbanerje (talk) 21:40, 13 May 2010 (UTC)
replies: text:  Agree.  It would be nicer to have clearer wording, but at least we have this discussion. --Ronz (talk) 22:17, 13 May 2010 (UTC)
thread_title: Definition

message: There needs to be a section added on effective lengths depending on the type beam that is being analyzed for example cantilever, Fixed/Free, or Fixed/Fixed which all refer to the type of supports the beam has. The effective length changes depending on the type of supports the beam has. Mechanics of Materials by Beer, Johnston, DeWolf, and Mazurek is an excellent reference for this as well as the entire article, I used it in my Undergraduate studies at University of New Hampshire.  —Preceding unsigned comment added by Jayman3000 (talk • contribs) 20:36, 1 July 2010 (UTC)
replies: text: I don't think it needs a section, but I just added a definition, which is important because the article refers to that quantity. I suppose this is what you mean. I just stole it from another Wikipedia article. Kallog (talk) 15:38, 2 July 2010 (UTC)
thread_title:  Effective Beam lengths 

message: As written this section does not distinguish FTB from LTB - both combine bending and twisting - and is not helpful.  It also would benefit from editing for style.  I recommend it be deleted or - better - clarified. Unfortunately I lack the expertise to do the latter.  — Preceding unsigned comment added by Mwregehr (talk • contribs) 06:34, 24 April 2011 (UTC)
thread_title:  Flexural-torsional buckling (FTB) 

message: I read their original report as early as they posted online at iMechanica.org. Actually I don't think it's generally speaking "buckling". It's just a kind of instability in a particular structure system. How the symmetry is broken decides which way the system deforms. All in all, I don't quite agree to category this as a section of buckling. Gareth (talk) 18:22, 3 October 2011 (UTC)
thread_title:  Tensile buckling 

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thread_title: File:Ziegler column.jpg Nominated for speedy Deletion

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thread_title: File:Continuous model tensile buckling0.jpg Nominated for Deletion

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thread_title: File:Tensile buckling discrete model.jpg Nominated for Deletion

message: I've found it interesting that the Johnson Parabola was never discussed.  This is more critical for short column buckling and offers an alternative explanation to the radius of gyration = 50 rule of thumb.  Unfortunately, I don't have any solid internet resources, though you can find proof that the concept exists through the following URL's:
http://inside.mines.edu/~jsteele/411/Lectures/L04StressStrain/L43Buckling.pdf
http://www.egr.msu.edu/classes/me471/thompson/handout/class07_2005S_Buckling.pdf  — Preceding unsigned comment added by 199.168.151.36 (talk) 20:43, 23 September 2015 (UTC)
thread_title:  Johnson Parabola 

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thread_title:  External links modified 

message: I was thinking about expanding the dynamic buckling section of this page (actually, I don't know if it will be a net expansion) sometime in the near future. Any objections?Rja13ww33 (talk) 17:58, 23 September 2020 (UTC)
thread_title:  Dynamic Buckling  

message: At the following web page https://pp.bme.hu/ar/article/view/20599 is available an article on a novel approach to the design of slender timber struts. I suggest incorporating a new paragraph or a reference to this article. Nettuno001 (talk) 06:52, 26 November 2023 (UTC)
thread_title:  New method for the design of slender timber struts