Adhesive vs cohesive

[liq001]

Hello ABAQUS users,

I am trying to modeling the adhesive vs cohesive in a a peel test. I am wondering is anyway that I can use cohesive contact of top of cohesive element? I am trying to understand the adhesive failure at the the interface vs cohesive failure in the cohesive layer. please help. Thanks

Bests
Lee

 

[FEA way]

I guess that by adhesive you mean cohesive elements (element-based cohesive behavior) and by cohesive you mean cohesive contact (surface-based cohesive behavior). Both approaches can be used to model adhesive joints in Abaqus. The differences between them are described in the documentation chapter "Contact Cohesive Behavior", paragraph "High-Level Comparison of Cohesive-Element and Cohesive-Contact Approaches".

 

[liq001]

@ FEA way. No, please see the attach for your reference. I would like modeling the adhesive as well as cohesive. anyway we can do it in abaqus?

 

[FEA way]

The aforementioned modeling approaches are meant for debonding simulations where you can model the adhesive as a single layer of special elements that can get damaged and removed or as a contact interaction with damage behavior. You define the failure criteria for the interface. Either way, only the whole interface can fail in the thickness direction. If you want to model damage/cracking within the interface then you will need multiple layers of regular finite elements and some more general fracture mechanics technique like XFEM, regular crack propagation or progressive material damage model.

 

[liq001]

So do you think I can use XFEM and cohesive element together?

 

[liq001]

and also my I ask can cohesive element fail in shear or tangent direction?

 

[SWComposites]

ok, to do this you model the adhesive material layer (where the "cohesive" failure mode occurs) with solid elements and non-linear material properties and some sort of failure criteria, and
you model the "adhesive" failure mode at the interface between the adhesive material and the adherend materials with Abaqus cohesive elements.
yeah, the terminology is VERY confusing.
but, you are going to need appropriate material properties for both the adhesive solid elements, and the cohesive elements. which means you need test data for these materials/combinations.

 

[FEA way]

Check the research paper "Combined XFEM-Cohesive Finite Element Analyses of Single-Lap Joints" by F.A. Stuparu if you are interested in such a mixed approach. Normally, you would need 2 separate analyses.

Cohesive elements can use the simplified traction-separation model or continuum description (any standard material model available in Abaqus).

 

[liq001]

@SWComposites Thanks for your inputs. May I ask if you have any such examples? Thanks again.

 

[liq001]

@FEAway. Thanks l, will look at the paper