Abaqus Explicit Cohesive Behaviour 1

[Peterle123]

Hi,
I am currently using Abaqus Explicit to model a Drilling operation for a composite. I want to evaluate the delamination that occurs during this process.
I modelled the Cohesive Behaviour with cohesive surfaces and use the interaction menue to connect the two plies. I used Surface tu Surface, Surface to Node Set, as well as General contact method, but when i start the Job I get this Error message and the Job will abort:
" Surface based COHESIVE BEHAVIOR cannot be used for contact pair interactions"
The Properties for the cohesive Material are in the picture below (Cohesive Behaviour is on Default). When I Run the job without the Interaction, there is no Error, so I think that my Interaction is somehow wrong. Can Anyone Help me?

https://files.engineering.com/getfi...b772-41ec-95ae-baf36219ef0e&file=Cohesive.PNG

 

[FEA way]

As the error says, in Abaqus/Explicit you can use surface-based cohesive behavior only with general contact interaction (not with contact pairs).

 

[Peterle123]

Thanks for the answer. I tried it with General Contact, but then i get this issue:

https://files.engineering.com/getfi...d4-e02a-44f0-8197-87978b11b744&file=Error.PNG

 

[FEA way]

That’s because you have to assign this property to selected pair of surfaces (within general contact definition). Use the "Individual property assignments" option.

 

[Peterle123]

Thank you. It works, you really helped me. May I asked one more question? Do you know what I can take for the "Power Law Exponent" or "BK exponent" in the mixed mode Behaviour, when i define the Damage Evolution for the cohesive? I cant find any value for my specific Material. I have no option to get it through experiments due to Corona.

 

[FEA way]

In such case it would be best to use values from literature or from exemplary analysis that can be found in the internet.

 

[Peterle123]

I only got these values:

https://files.engineering.com/getfi...d-dbe1-4e62-8f0c-55c2aa0a258c&file=Values.PNG

Can i somehow Calculate the Exponent? Or can I not use mixed mode Behaviuor? Then I only need the Fracture Energy:

https://files.engineering.com/getfi...6946-4200-84d7-a541e0b07b4b&file=No_mixed.PNG

Because I need to use this cohesive from the Paper, thats what my thesis is for.

 

[Ravi K Mudragada]

Peterle123,
From the literature(Civil-Structural Engineering), it is suggested to use BK Exponent as '2' for the brittle materials.