Why do I have delamination with cohesive surface in Abaqus when the damage value is still zero?

[Johanes Wijaya]

Hello, I'm a mechanical student who wants to make a peel-off model test for sandwich composite. I design the model using the cohesive surface to bond the composite skin and the core. But when I run the simulation I notice that the delamination occurs before the damage value reaches one, I have tried to fix it, even though I have made a new model but the results have no difference. Here I attach the capture of the result as well as the file (I'm using Abaqus 2017). I would really appreciate it if you can help me to solve my problem.
Thank you!

 

[FEA way]

Use the "Adjust secondary nodes in set" option to ensure initial contact. Double-check the cohesive behavior and damage settings, make sure that all the values used there are correct. Maybe try with different criteria.