Hi all,

I study dynamic materials and I am hoping to run a reasonably simple tensile test simulation with a 12.5 x 9 mm custom material. I would use a Nonlinear dynamic study and I would upload my stress-strain curve (over 1100% strain) obtained from in lab elongation into the model type nonlinear elastic. 

   Thickness 50 microns

   Poisson's Ratio 0.5
   Mass Density 300 kg/m^3
   Tensile Strength 7 MPa

I have been trying to run a ~200% elongation however at the first step increment I would get this message:

"The tangent modulus was found either (1) higher than (or equal to) the elastic modulus, or (2) negative in the stress-strain curve definition. Would you like to stop the solver and check the data input? Otherwise, the solver will ignore the invalid data and only keep the ones with the tangent modulus lower than the elastic modulus and greater than (or equal to) zero."

From here I the study would just fail and end.