Hi, 

I am working on a XFEM fatigue analysis on a ESE(T) specimen for s355 steel with: 

*Step, name=Step-1, nlgeom=NO, inc=1000
*FATIGUE, TYPE=CONSTANT AMPLITUDE

and 

*Fracture Criterion, type=FATIGUE, mixed mode behavior=IRWIN

Which is giving the error: THE STRAIN ENERGY RELEASE RATES ARE TOO SMALL TO LEAD TO ANY FATIGUE CRACK GROWTH IN ANY ELEMENT IN THE MODEL and I do not no what could be the problem. Someone that has experienced similar problems?