Sandeep Medikonda
Ansys Employee

Hi Fabricio,

  It looks like this is the engineering stress, is that correct? If so, you would have to convert this to true stress-strain data. Also, it looks like you don't have enough data points there. The reason why it is not recommended is since stiffness is zero it will introduce instability into your analysis.

  Check out this article, you might find useful.