tensile test using abaqus #1: failure of sample tensile test using ductile damage (element deletion) 

Good question!

this indeed is an interesting question. But once I did FE modelling of square crashbox with some Q1 papers and experimental data as refference. By using just the model, the first folding occured at the front of the structure while from what I read, at the real situation the folding initiation might occur at random spot but mostly at the near middle of the crashbox. I can't really explain it myself why the FE modelling does so because it was not my focus since in crashbox problem we simply make some indentation for folding initiation

i am looking for that too. damage for fatigue test. Have you done that?

j'ai le meme problème

nice try