0.2 % offset for yield point computation
I have got some experimental readings of true strain vs true stress. I have fitted a straight line to the elastic part of the curve as shown in the attached figure.
As seen, the fitted straight line starts not from the origin (as the data was noisy here) but at an intermediate point (here where stress = 400 MPa)
Now, I want to draw a lien parallel to this line at an offset 0f 0.002. My question is should the offset be measured (horizontally)from the origin or (horizontally) from the point corresponding to sigma = 400 MPa?