Introduction to Drucker's Stability
A material model satisfies Drucker’s stability if an increase in strain results in an increase in stress. In some cases it can be important to enforce that a material model is Drucker’s stable. In the video below I will show how you can easily achieve this in MCalibration.
In short, you can achieve this by setting a penalty weight in a load case for predictions that are not Drucker’s stable.

The following video has all the details.