Right now I am trying  to  learn the use of damage model in SIMULIA 3DEXPERIENCE.  I would like to perform simple tensile test  using  ASTM E8  &  would like to check crack and element deletion while performing uniaxial tensile test.  But for that I need fracture strain value, I have done some google & got some idea such as stress strain data required (mostly true stress vs strain) if not then Engineering stress vs strain, from that plastic strain and then fracture strain, but I want to understand the calculation behind this fracture strain. Do we have some data/step by step method?

There are some other terms available facture energy and displacement at failure. Does all this data required or only facture strain will provide the result ? ​​​​​​​