Compression stress-strain data negative or positive?
 

Hi everyone,

this is probably a silly question but i'll ask it anyway.
I wanted to try some material models in ansys and i'm not sure how the input for compression works.

Because i've seen some examples in the Ansys help tool where they put compression strain-stress data as positive values.

For example for a cast iron plasticity model:

TB,UNIAXIAL,matid,1,3,COMPRESSION
TBTEMP,10
TBPT,,0.203E-02,0.300E+03
TBPT,,0.500E-02,0.500E+03
TBPT,,0.800E-02,0.581E+03


I wanted to try for example some hyperelastic material models and i don't know how i could put some unaxial stress strain data under compression?Positve,negative?

It would be nice if someone could help me out.