isotropic hardening

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.

For those who may be interested,

 I have put together a paper describing 1D plasticity for a variety of cases of isotropic hardening.  The material is not new, but hopefully it is written with enough detail that it will help beginners learn some basics of computational plasticity.  The notation and material closely follows "Computational Inelasticity" written by Simo and Hughes.