Talk:Stress–strain curve
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[edit] 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
[edit] 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
[edit] 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)
[edit] 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
[edit] 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
[edit] Area under the curve
I am a student who is currently studying the Stress-Strain graph in practice from an exam.
A question related to this topic asked to prove that the area under the graph is "the energy converted per unit volume" (as quoted directly). I was stumped and referred to Wikipedia for help, but to my suprise there is no proof for this.
I know that the area under a graph is deduced by multiplying the values related to a corresponding y-axis and x-axis range, such as a velocity-time graph which has an area under the graph representing distance travelled.
So in respect to the units relating to the graph variables, stress is measured as a pressure and strain (as defined in this section) is "derived from measuring the deformation of the sample". Upon further reading on strain under material sciences (Strain (materials science)), it appears that strain is a dimensionless quantity, as the units of the lengths cancel out.
Therefore, the area under the graph is Stress multiplied by Strain (in respect to units), which leads to Pressure (Force/Area, Nm2 or kgm-1s-2) multiplied by a dimensionless quantity, which still gives a value measured in Pressure.
Which leads me to my question, why is the area under the Stress-Strain graph defined as "energy converted per unit volume" when TECHNICALLY it should be calculated and presented as a Pressure?
I know that the base units measured for energy per unit volume is the SAME as pressure (kgm-1s-2), but what I don't understand is how they arrived at this solution. Is there an alternative method which can be used to arrive at the definition given above?
Thanks.
INITIAL POST: Eug.galeotti (talk) 10:37, 26 March 2008 (UTC)
EDITED: Eug.galeotti (talk) 10:47, 26 March 2008 (UTC)
