plot the stress-strain curve in ABAQUS

[raminbabaei]

Dear All

I want to plot the true stress-true strain curve for simple plasticity case. I use field output and plot summation of the reaction force devided by refrence area times by (1+eng. strain) as true stress and similarly ln(1+eng. strain) as true strain.
but I got the wrong results in both young modules and yield stress.
I would be appreciate, if you can help me.

Ramin

[Jorgen]

It sounds like you are doing it right.

Is there a reason why you don't directly output the true stress and true strain from Abaqus?

[raminbabaei]

actually, I have a unit cell and I want to stress-strain curve for whole of the unit cell not just one node.I think ABAQUS does not give me this curve directly.
so I should use the reaction force on the surface and devided by area to obtain true stress.this metho works properly for elastic case but it gives wrong answer for plastic region.

[Jorgen]

OK, I see. It sounds like you using a correct approach.
I would recommend that you double check your approach to make sure there are no errors...