# power law

## Isotropic hardening law

Hi all,

I have come across the two relations where aim to describe the isotropic hardening of a material

Power law:

R = Kεpn R is the variation in stress from initial yield, εp is the plastic strain where K is the strenght coefficient and n is the strain hardening exponent as observed in Ramberg Osgood equations.

Exponential law:

R = R∞ [1-e(-bεp)] where R∞ is the saturated value of the R variation, b is the rate at which the sauration is reached.

## Modeling Metal forming in Abaqus...

I'm currently working on my master thesis which is in the area of metal
forming simulation...

I have one question,,, when adding material plasticity in Abaqus using the
power law...

to what limit shall i go in the tabulated form is it to 100% plasticity or
to the maximum strain the material can take...

in other word,,, if the power law is: σ =250*εp^0.123...

shall i inter the values till at σ=250, ε=1... or shall i stop at let say ε=0.25...

Regards,,,

Was 