peteroznewman
Subscriber

Riccardo,

The laboratory test measured compression force and displacement as the raw data from the sensors. That is what you should try to reproduce. Get that raw data if you can. Typically, the Force is converted to Engineering Stress by dividing by the Initial cross-sectional area.  The displacement is converted to Engineering Strain by dividing by the Initial Gauge Length.

For a Plasticity material model, the Engineering Stress and Engineering Strain have to be converted to True Stress and True Strain. Did you do that?  Are you using a Plasticity model, which one? When Ansys solves a model, the output is True Stress and True Strain. What have you done to plot the yellow curve?

What is this material?  How is it possible that the force could drop to zero? Do you have images of the test setup and the sample shape before, during and after the test?