Hello
How can depict the true stress-strain curve for some cold rolled specimens?I'd like to achieve the yield stress for some cold rolled samples and basis of them, achieve the Voce equation parameters.I attached one paper. In this paper, the author have depicted a curve Fig.2. but i don't understand how that curve accurately depicted.
it is very nice of you comment your advice about it.
Dear Amir,
Equation 2 seems to be a modified Voce Equation with the last term added to accommodate Stage IV work hardening. Before trying to fit the modified Voce, I would recommend trying to fit a regular Voce equation. To do that, plot work hardening rate (derivative of true stress with respect to true strain) versus true strain. This is called the Kocks-Mecking plot. Starting at around 2 to 3 GPa, you will see that work hardening rate becomes a linear function of true stress. The slope of this line is k1 in Equation 2 and the y-intercept is sigma HR * k1. You need to find the value of sigma tr by best fit methods. Also observe if the linear regime deviates at low work hardening rates and what the extent of deformation at that level is.If it is extensive, you can then add the last term.
Good luck,
Murat
Murat Tiryakioḡlu I have one question about the stress-strain curve which was plotted in the paper. the solid line (below 0.2 strain) has been achieved just by a simple tensile test data? I know that a stress-strain curve begins linear at first and have a ultimate value and finally decreases at fracture point. but this part of curve is just linear.
I would be grateful if you could take a look at this.
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