Low Cycyle Fatigue Analysis with XFEM

Hello Everybody,
I am studying the overall problem is a crack propagation analysis due to fatigue loading for any kind of structure made of steel. I am struggeling to verify the Low-Cycle-Fatigue-Algorithm (Paris-Law) in detail. Basically, I can reduce my question to "How is the element length predicted in the LCF-Analysis and how can i extract the used value from the odb-file?". And the second question: "How or what is stored as kind of damage for uncracked (not fully cracked) elements for a three-dimensional problem if the ENRRT increases for the next step?"
I have noticed that the crack length da for the Paris-Law for elements with short cracks at the edge is not clear, resulting in wrong number of cycles.

Thanks for any adivce!

(I am using Abaqus2018)