Plastic stree-strain graph?

Question

Does anyone know where on the net there is a stress-strain graph for some kind of plastic?

Answer 1

Polymer Stress-Strain Curve available at:
http://www.doitpoms.ac.uk/tlplib/polymers/stress-strain.php

Answer 2

I have not seen one - however I can tell you that the stress -strain behavior of composites is very non-linear; the plot begins to roll over immediately upon initial loading. This occurs because as the fibers begin to fail, the stiffness is lost. This is a non-recoverable condition, so any repeated load cases generally result in a hysteresis behavior. I think plastic would act in a similar fashion, unless it was cold enough to be brittle; in which case the non-linearity would be reduced to the point where it would appear to be linear to failure.

Answer 3

Basically, you are just graphing Hooke's Law (i.e. stress = strain * Modulus) where Young's Modulus is the slope of the line. So, just plot y = mx + b where b is equal to zero, m is Young's Modulus, x is strain, and y is stress. You will get a straight line up to the yield stress where the line should will get flatter (i.e. slope approaches zero) up to the point of the ultimate strength of the material.