Stress-Strain Conversion (Hyperelasticity)

[Dave442]

Hi all,

I wish to perform an analysis on a hyperelastic material. Reading the manual I discovered that nominal (engineering) stress and strain data is required for defining a hyperelastic material model.

The experimental data I have is presented as Cauchy stress vs. stretch. From my understanding of mechanics Cauchy stress is True stress, is this correct?

Also, I was wondering if it is acceptable to convert Cauchy stress to nominal stress by rearranging the equation given in the plasticity section of the ABAQUS manual, ie:

s_true = s_nom / (1 + e_nom) where [s = stress, e = strain]

Any insight would be greatly appreciated!

Regards,
Dave

 

[Dave442]

*correction:

s_true = s_nom * (1 + e_nom) where [s = stress, e = strain]