Talk:Euler–Bernoulli beam theory

message: I forgot to login before creating this article. --Yannick 23:42, 17 Jun 2005 (UTC)

message: I think the cantilever glass beam is a nice picture but does not help at all, and does not add any value to the article as I can not understand it, even if I have a strong knowledge on this subject.
It should be deleted or replaced by another more understandable example...  — Preceding unsigned comment added by 119.77.8.4 (talk) 01:06, 2 March 2012 (UTC)
thread_title:  Suggestions for Further Work 

message: # I'm curious as to when the theory was proven by laboratory experiment.
# The nature of Bernoulli's and Euler's collaboration could be expanded.
# Stephen Timoshenko's History of Strength of Materials (Dover Publications, Inc., New York, 1983) would probably provide more information. Anybody got a copy?
--Yannick 23:42, 17 Jun 2005 (UTC)
replies: text: In my classes, the prof told us that Euler and Bernoulli derived the equations from the full theory of elasticity matrices, which were already known, and empirical proof came later. I still have extensive notes on the derivation.--Yannick 18:34, 3 July 2006 (UTC)
thread_title:  History 

message: Two more assumptions are: 
Material should be homogeneous.
Material should have continuity.
:I believe those are assumptions of the theory of elasticity, not of beam theory.--Yannick 04:23, 18 September 2006 (UTC)
replies: text: That would be more useful than the current page.  Having both would make it much more complete. - EndingPop 00:55, 13 June 2006 (UTC)
thread_title:  Addendum 

message: I basically reverted the main equations in the "practical simplification" section. My main reason is that a major error was introduced on December 22, 2005, by 131.151.65.70 simply by changing '=' signs to '+' signs. However, I also reverted other ongoing degradation of the equations. I changed the load variable back to 'P' from 'F' for consistency, because F was defined earlier in the article as internal axial force. I'm guessing it was originally changed to match the diagram, but changes like that should try to make the ENTIRE article consistent, not just one section. In this case, I would prefer changing the diagram to show a tip load of 'P', but if we go with 'F', then the variable for internal axial force should change to something else for the whole article. I also reverted 69.241.225.246's recent change at the same time because although concise equations may be pleasing to mathematicians, they make it harder for the intended audience (engineers) to read, and key information was lost in the edit: that these equations give the MAXIMUM deflection and stress for any point in the beam. Also, if we are going to express these equations as proper functions of '(x)', then 'My' should also be expressed as 'My(x)'. I didn't want to do that because this is a basic example section which should minimize the potential to confuse newbies.
No doubt there is a way to formulate these equations that will satisfy everyone's concerns, and I'll try to work on it if I get a chance. But if you want to take a try at it, please look at the entire equation, and see how it fits in with the rest of the article. A small change can really mess things up.--Yannick 04:14, 18 September 2006 (UTC)
thread_title:  Please don't edit equations recklessly 

message: That image of the cantilevered beam in the Boundary Considerations section seems wrong to me.  In the image, the free end remains horizontal.  This seems to imply that there is zero rotation, but non-zero deflection at the end of the beam.  Somehow we've fixed rotations and not displacements, which isn't a possible BC presented in the section.  If I'm wrong on this, could someone please explain why? - EndingPop 22:16, 3 March 2007 (UTC)
thread_title:  Cantilever Image 

message: The cantilever with a distributed load example appears to have incorrect equations for deflection.  In particular, if I assume that fixed end of the beam occurs at either x = 0 or x = L, there is a nonzero deflection, but the fixed end should have a zero deflection.  Also, the equations do not match one of the quoted external links "Beam Deflection Formulae".  I don't know the correct formula myself.  Could someone please fix it?  Thanks. Eerb (talk) 18:20, 13 June 2008 (UTC)
replies: text: There are more issues. I asked the author of these examples to fix these. Crowsnest (talk) 22:04, 13 June 2008 (UTC)
replies: text: The author does not react, so I added tags to the relevant "Beam examples" section. 11:11, 22 June 2008 (UTC)

text: There are errors in this section. If they are not removed and the examples are not provided with reliable sources, I will remove this section. Crowsnest (talk) 07:59, 1 July 2008 (UTC)

text: I moved the beam examples over here, for the time being, since they contain errors and lack verifiability. They are nice, so please clean them up, add citations and thereafter put them back, if you like. Crowsnest (talk) 08:32, 1 July 2008 (UTC)
thread_title:  Cantilever example 

message: Why should this theory be valid for isotropic elasticity only? 
It should also be valid for orthotropic elasticity.  —Preceding unsigned comment added by DonQ1906 (talk • contribs) 03:09, 10 October 2008 (UTC)
thread_title: Orthotropic elasticity

message: The name of this article should be changed to Euler–Bernoulli beam theory as it is more than only the Euler–Bernoulli beam equation. This would make it consistent with the naming in the first paragraph as well. 145.53.180.22 (talk) 16:08, 22 January 2012 (UTC)
replies: text: Indeed. -- Mecanismo | Talk 21:06, 22 January 2012 (UTC)

text: * I've took the liberty to rename the article, in order to correct its name. -- Mecanismo | Talk 20:53, 27 January 2012 (UTC)
thread_title:  Article name change 

message: I have made changes to correct the sign convention inconsistency pointed out above.  Two inconsistent figures were removed.  
In the History section and in the Static beam equation section a sign convention was adopted in which the positive z direction is up and the positive x direction is to the right.  Since this sign conventions is the first used in the article, I followed it and added the direction of y as being into the figure as required by the right hand rule.  A problem was created when someone added figures with y positive up and z positive out of the paper.  Removing these figures restores consistency of the sign convention in "Static beam equation" and "Derivation of bending moment equation" as I see it.  I don't know why someone added these figure with an inconsistent sign convention.  I hope he or she doesn't cause trouble by putting up a fight to have their figures retained.  RHB100 (talk) 20:21, 8 February 2017 (UTC)
thread_title:  Sign convention corrections 

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thread_title:  External links modified 

message: Can someone walk through the derivation of the final boxed equation for the moderate rotation (small strain) beam equation, assuming uniform cross section and no axial load? I cannot reach the same conclusion. Here are my steps:
Assumptions in article state "no axial load". Axial load is previously defined as f(x). Thus, this means that the internal axial force N(x) is constant (but possibly non-zero!). In addition, the extensional-bending coupling term B_{xx} is zero if the coordinate system is a centroidal coordinate system. The governing ODE then becomes
EI\frac{d^4w}{dx^4} - EA\frac{d^2w}{dx^2}\left(\frac{du}{dx}-\frac{1}{2}\left(\frac{dw}{dx}\right)^2\right) = q(x)
I don't see how the \frac{3}{2} term or any other simplification in the final boxed equation was derived. Can anyone comment on the derivation? 
Rchensix (talk) 16:11, 19 April 2019 (UTC)
thread_title:  Derivation of final moderate rotation (small strain) beam equation 

message: I have a fairly technical background, but not in engineering or mechanics. The section on the derivation of this equation begins by discussing something called a "fiber" without defining it explicitly, providing a mathematical definition, or providing common-sense intuition for the concept. There are no links to further resources that could provide the necessary background to continue. This should be remedied. i.e.: What is a fiber? Likewise, terms/concepts such as "dθ" are introduced without adequate context or definition. As-is, this section is unreadable as an introductory/didactic text for the layperson. 2A00:23C7:85A7:7801:7568:32E:9ACA:7732 (talk) 12:03, 8 October 2022 (UTC)
thread_title:  Inadequate definition, introduction, or citing of basic concepts used to derive the equation