# Talk:Elastic modulus

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## Merge from elastica theory

i don't fully understand either topic, but they seem to both be short articles on very similar topics. could do with help from a proper physicist. i say we merge. thoughts? mastodon 15:38, 19 March 2006 (UTC)

Elastic modululus is Young's modulus; an equation relating strain to stress to give the strength or resisitance to stretching of a material. The other one is about the elasticity of a material in different directions, how far it will stretch/bend ect.

I don't really think the two are closely related at all, but it's difficult to tell because of the extreme shortness of the Elastica theory. Ingoolemo talk 23:08, 21 March 2006 (UTC)
Completely unrelated. Will expand elastica soon. deeptrivia (talk) 05:02, 29 March 2006 (UTC)

### Unrelated Topics

The two topics are completely different.

The Modulus of Elasticity is a physical propterty of materials. It is the ratio between stress and strain. Once the Elastic Limit is met/surpassed for a particular element it can no longer be loaded/unloaded without resulting in deformation. As in the case of steel, the element stretches like taffy after reaching its Elastic Limit. In a stress/strain diagram, the Modulus of Elasticity is the slope of the line. When the Elastic Limit is reached, the graph is no longer a straight line. (The Modulus of Elasticity of structural steel is around 29,000,000 psi).

It seems as though the other topic is related more to deflection, which is basically how much something bends when it is loaded. Say, if you have a beam acting as a bridge with a fixed support on one end and a roller support on the other (rollers account for any change due to thermal stretching and allow a little horizontal movement in the beam so it doesn't get put under too much pressure). If you add a point load (that's an unmoving load-- eg a car or something) to the beam, the deflection is the maximum "sag" the beam moves from its original position to account for the loading.

There is a connection between the two topics in that deflection is the result of loading an item and the deflection is related to the Modulus of Elasticity. However, the two topics are not the same. One appears to be a theory concerning deflection and how a material bends and the Modulus of Elasticity is a measurable ratio of loading up to the Elastic Limit, when deformity/failure of a matieral begins to occur.

jadewik 30 March, 2006 (My first wikipedia post/comment... go easy on me *grin*)

## Axial Modulus of Elasticity

Where does this fit in? It has no entry in Wiki, but Googling it seems to be used in engineering texts. 203.213.7.133 02:03, 20 March 2007 (UTC)

Seems to be another name for http://en.wikipedia.org/wiki/Young%27s_modulus. Can't give a reference, but the numbers seem to match. 203.213.7.133 03:30, 20 March 2007 (UTC)

## Elastic Moduli Edits

Concerning User:Berland's edits of Poisson's ratio, Shear modulus, and Bulk modulus, I think its good to have a separate section showing how that particular modulus relates to other moduli, even though it is duplicated in Elastic modulus. Also, I think the very useful table in the Elastic modulus article should default to showing, so that a single click is required to bring it up, rather than two and I have changed it accordingly. I will revert the edits to the individual moduli articles, unless you have strong objections? PAR (talk) 21:05, 23 November 2007 (UTC)

I don't see the need for replicating the formulas, at least not when the formulas in the table are initially visible. I do however see that fact that all the elastic moduli are connected in this way is not clearly conveyed having it only mentioned in the table below. You are of course welcome to improve on this. You may also discuss the default visibility of the table at Template talk:Elastic moduli, where there are some thoughts already. --Berland (talk) 21:20, 23 November 2007 (UTC)
Ok, good, I have commented there also.

## confusion of two topics

quote from Young's modulus:

"In solid mechanics, Young's modulus (E) is a measure of stiffness. It is also known as the Young modulus, modulus of elasticity, elastic modulus or tensile modulus..."

this says that Young's modulus and the elastic modulus are the same thing, but there are different pages on each one. These pages need to be merged if they are the same thing or if not it has to be clarified what is going on. --LeakeyJee (talk) 02:08, 18 April 2008 (UTC)

Yes, I agree. This is confusing, especially as "modulus of elasticity" also redirects here, and there is no clear definition on any differences between the two. I don't currently know enough to do much about it, but somebody needs to clarify this or possibly merge the pages. GeiwTeol 00:08, 20 April 2010 (UTC)
I've reworked the intro of Young's modulus to explain how Young's modulus is incorrectly called the elastic modulus. Hope this clears up the confusion. Wizard191 (talk) 17:33, 20 April 2010 (UTC)

## mathematical symbols

It would be helpful if someone could put a link to the symbol used in the mathematical definition, specifically the equals sign with the letters 'def' above it.

$\stackrel{\text{def}}{=}\$

Is this shorthand for 'defined as'? I can't find it in Table of mathematical symbols. Wikid (talk) 06:13, 13 July 2008 (UTC)

Yes, it means "is defined as". Wizard191 (talk) 02:37, 20 November 2008 (UTC)

## Flexural modulus

I'm currently researching the flexural modulus (which doesn't have an article...quite deterring), however am not well versed with the concept. According to [1] it is a bending form of the elastic modulus. As such I think it should be added here, but I'm not certain that my source is completely correct. I would like a second opinion before I go and add erroneous info. That source also states there is a torsional modulus, which, if true, should be added as well. Wizard191 (talk) 02:41, 20 November 2008 (UTC)

## Young's modulus for compressive load

It is written: "Young's modulus (E) describes tensile elasticity, or the tendency of an object to deform along an axis when opposing forces are applied along that axis; it is defined as the ratio of tensile stress to tensile strain."

For axial compressive load the term Young's modulus is not valid? Sreerup Banerjee (talk) 19:29, 29 April 2009 (UTC)

I am not sure that I agree with the statement that Young's modulus does not apply to axial compression. As long as the material is isotropic and within the elastic limits for the material Young's modulus does not care which direction the stress acts and the value is the same in both tension and compression. 74.60.57.253 (talk) 01:24, 1 August 2009 (UTC)

## Deformation of volume

"...the tendency of an object's volume to deform when under pressure...." The volume of an object has no form; it's just the size of a region of space, measured in cubic units. Shouldn't "deform" be replaced by "change"? Unfree (talk) 20:06, 9 November 2009 (UTC)

Quite right; I've attempted to fix the definition. Let me know what you think. Wizard191 (talk) 19:10, 11 November 2009 (UTC)

## Correction

Since the denominator becomes unity if length is doubled, ( for such big numbers the length should be multiplied be euler number and not 2 ) —Preceding unsigned comment added by Gkourtis (talkcontribs)

## Dimensionless vs pressure-dimensional

The Poisson's ratio is listed as one of "elastic moduli". Does anybody care about that it's dimensionless? Incnis Mrsi (talk) 09:50, 28 July 2012 (UTC)