Talk:Stress–strain curve

Slope change
Usually there is a change in slope when passing from Elastic to Plastic region, and this is the sign that we passed the Elastic region. Please correct. —Preceding unsigned comment added by Hakapes (talk • contribs) 11:06, August 8, 2005

Measurements needed
hio, do not forget to discuss different measurements of stress strain, like engineering stress strain diagrams... important stuff. —Preceding unsigned comment added by 24.156.183.209 (talk • contribs) 02:41, October 27, 2005

I agree - the true stress-strain curve overlay (red and blue curves) indicates that the rupture strain is the same in both cases (engineering and true). This is totally false, and such a common misconception. Graphic should be improved. I don't have permission to upload images. :| — Preceding unsigned comment added by 212.211.159.227 (talk) 05:26, 6 October 2017 (UTC)

Layout and extra detail
No insult intended but the previous layout with huge figures and little sentences between them was, shall we say, less than attractive and certainly not consistent with most wikipedia articles. It's still not perfect but I think it's a step forward. Alternate opinions are welcome.

At the moment the information is a little limited and naive - it reads a bit like an 1st year text book. I've tried to add a little more detail but I've run out of time. I'll get back to it when I can (after the hols I guess)

Things to do:
 * Precise definitions of elastic limit, proportional limit, yield, luders strains, uniform elongation, necking, etc.
 * Considere's criterion for instability?
 * Better links between Yield (engineering), Stress (physics), Tensile stress, etc
 * Expand brittle materials section
 * yield curves of polymers and elastomers
 * brittle/ductile transitions? Maybe not
 * Merge with yield article? Maybe not
 * Non tension - torsion, bending, etc?

Cheers, Slinky Puppet 19:02, 20 December 2005 (UTC)

More needed
needs heaps more info (see Materials by Callister) and some references —Preceding unsigned comment added by 60.240.163.160 (talk • contribs) 09:35, September 18, 2006

Agreed, someone please help revamp this article. 69.181.153.214 (talk) 05:27, 24 January 2012 (UTC)

Figure 2
Where is the "figure 2" spoken of in the text? —Preceding unsigned comment added by 80.201.9.169 (talk • contribs) 08:07, January 10, 2007

Figure 2 should be modified. The points labeled as "Yield Strength" and "Ultimate Strength" should read instead something like "Yield" and "Ultimate Point." The "Strength" pertains only to the stress component, whereas your labels indicate points on the stress/strain diagram. Each point indicated (yield, ultimate, and fracture) have a stress and a strain associated with them. Hermanoere (talk) 21:50, 7 January 2020 (UTC)

Translate images
these images are only avilable in Dutch wikipedia: please download, translate, and upload them.

(Saeed.Veradi (talk) 14:48, 23 February 2009 (UTC)).

Ductile/brittle transition
As far as my understanding goes, the ductile/brittle transition is a temperature dependent phenomenon that is unrelated to the stress-strain curve; see ductility. Unless this is a different phenomenon, it shouldn't be included in this article. Wizard191 (talk) 12:51, 10 September 2010 (UTC)

Use "F" for force rather than "P"; reserve "P" for pressure
I believe it would improve the page to use "F" for force, rather than "P." The page on "strength of Materials" uses F for force, so using F would be more consistent with other Wikipedia pages. I also believe it is easier to use F for force and reserve P for pressure.


 * I corrected the image. Wizard191 (talk) 18:19, 17 May 2011 (UTC)

Not just applicable for metals
Tensile testing is also done for plastic sheets (films). Depending on the type of plastic and on how the plastic was produced, the stress-strain curves can look quite different. Additionally the stress strain curve can look different for a plastic film depending on which direction the strain is applied (for extruded or blown films). Sometimes it will have two yield points. The tensile strength is usually at the point just before the sample breaks, but not always. Tensile testing is routinely done by the folks who make garbage bags. Not a great deal of effort is needed to produce a sample for testing. Sample cutters cut a uniform width strip from a piece of material. --71.214.208.91 (talk) 05:45, 17 June 2012 (UTC)

Figure 1
Figure 1 shows that the equation for shear strain is (e = l/L) where 'l' is the additional length due to elongation and 'L' is the original length of the material (based on the diagram of a cylinder). This would produce the correct strain for elongation of the cylinder where, for instance, a lengthening from L=1 to L=1.1 (which would lead you to believe that l=0.1 based on the drawing) would give e=(0.1/1)=0.1. However, if the material was under compression and shortened by 0.1, it would be easy to come to the incorrect conclusion that L=0.9 (despite the fact that L=1 by definition) and l=0.1 (which is also incorrect) thus giving us a strain of e=(0.1/0.9)=0.11.

The cylinder should use 'L' to denote the original length of the cylinder(which is a constant value in our equation for strain). 'l' should be denoted as the overall length of the cylinder after it has been deformed (whether elongated or shortened). Then, the defintion of strain will be e=((l-L)/L). This is an important concept since it introduces the fact that negative strains are possible.

The figure needs to be replaced. — Preceding unsigned comment added by Kps16 (talk • contribs) 14:40, 2 August 2012 (UTC)

Error in slope formula
Since the revision "SVG version for stress-strain curve" of 5 May 2020, the slope formula on Fig.1 has changed from Rise/Run to Run/Rise.

Plschfr (talk) 11:59, 6 May 2020 (UTC)


 * Well spotted! Thanks for drawing it to our attention. I have alerted the User who produced the diagram and inserted it in the article - see User talk:Nicoguaro. Hopefully, this User can fix the errors. Dolphin ( t ) 13:18, 6 May 2020 (UTC)


 * User:Nicoguaro has fixed the error in his diagram. I have thanked him on his Talk page. Dolphin ( t ) 22:12, 6 May 2020 (UTC)