Stress and Strain, load and extension

[Big-Daddy]

Firstly, does a stress vs. strain graph for a material always take the same general shape as its load vs. extension graph (with the same important points, e.g. UTS, having the same shape and corresponding to the same thing)?

Secondly, what do the stress-strain and load-extension graphs look like for a metal wire, steel spring, rubber band and polyethene strip, and do these graphs all have all of the main points (i.e. limit of proportionality, elastic limit, upper yield point, lower yield point, UTS and breaking point) at separate points in the graph?

 

[technician]

stress = force/area so as long as the cross sectional area does not change (which it does !) then a graph of force against extension is essentially the same as stress against strain.
Strain = extension/original length so a graph of stress against strain should be the same (essentially) as a graph of force against strain