Cohesive Behaviour

[198039A]

I am currently modeling a shear-lap model of CFRP/Concrete composites with three parts: CFRP, Adhesive, and Concrete. I have modeled the Adhesive section using cohesive elements. To represent the bond between CFRP and adhesive I used a tie constraint because no slip or debonding were noted during the experiments. And I used a surface-to-surface interaction with tangential behaviour (Mechanical) to represent the bond between Adhesive and Concrete. The overall behaviour seems okay with tangential behaviour, but the pull-out load is very very low compared to the experiment. Therefore, I am trying to use a cohesive behaviour instead. But I am getting an error message that cohesive behaviour cannot be assigned for this particular interaction.

Can anyone advise me, how I can improve the current model and why cohesive behaviour is not working?

 

[FEA way]

You can try using surface-based instead of element-based coheaive behavior. There are several differences between these two approaches but generally the former is easier to model (it ignores the adhesive layer thickness though).