Hi, everyone. I want to ask a question about the JC damage model that has been bothering me for a while now, and I feel that it might turn my previous knowledge upside down. Is the strain value calculated by the Johnson-Cook damage model used in Abaqus software the fracture strain? Or is it the damage initiation point strain?
I found some articles that indicated that the strain calculated by the Johnson-Cook damage model was the equivalent plastic strain at the point of damage initiation. In contrast, others indicated that the equivalent plastic strain at fracture was calculated!
I'm really confused. Can you help with this? Thanks a million!
Yh Chen, while working with the JC material definition, you must remember that, the strain value calculated by the JC damage model in Abaqus software is the equivalent plastic strain at the point of damage initiation. The model considers both damage initiation and damage evolution, and it can be used to predict the fracture behavior of materials under various conditions. For the above material you have included, you can use the input file, I@ have included here.
According to the fomulation in the paper you extracted the graphic from, It corresponds to the fracture point.
When fracture occurs, the damage variable is equal to one, and the stress to zero. Considering the evolution of the damage parameter, it's equal to one when the plastic strain is equal to the fracture strain. Eq. 8 from your paper.
It's somehow possible to determine an other parameter, corresponding to damage initiation strain. Take care to model formulations in different articles, they are almost everytime different and hence, use different parameters definition. I will give an eye to the official abaqus documentation to give you further details when I will access to it.
Regards
Corentin
Corentin Levard, I'm sorry to bother you again. After checking the official Abaqus documentation, I think you may be wrong, as the Abaqus documentation indicates that the failure strain calculated by the Johnson-Cook damage model should correspond to the equivalent plastic strain at the onset of the damage, Instead of the equivalent plastic strain corresponding to the final fracture point.
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