Single lap joint simulation using Abaqus 2017

[Emile Pantaleao]

Hello,

I am studying the stress repartition inside of the adhesive layer of a single lap joint (SLJ).
The substrates and the adhesive are considered elasto-plastic with a hardening plastic behavior obtained by SLJ shear tests and tensile tests.
The model 2D plane strain, the solver is Dynamic, Explicit.

My goal is to obtain the elastic and the plastic hardening behavior using an Abaqus model.

However the adhesive behaves incorrectly.

Here only the first row of elements of the mesh is deforming. The stress is expected to be higher in the corner of the adhesive and might be the reason for the high strain.
However, it should be shared with other elements.

This strain does not appear when the adhesive's behavior is only elastic.

So far I have tried the following methods to fix the problem without success:
- interface (substrate/adhesive) behavior : cohesive, no debonding,
- interface behavior : tie constraint,
- merging the nodes of the interface,
- refining the mesh,
- change from implicit to explicit solver,
- remeshing rules and adaptative mesh for the adhesive layer.

No matter how refined the mesh is, only the first row of elements is deformed.

This picture shows how the adhesive is expected to deform :

[Parametric study of hot-melt adhesive under accelerated ageing for automotive applications, E.G. Koricho et al.]

Thank you.

 

[SWComposites]

I think the issue is related to the very low stiffness properties of the adhesive. You really need to somehow validate all of the material properties that you are using.

One option would be to use a single row of elements thru the adhesive thickness.

 

[Emile Pantaleao]

SWComposites,

Indeed the difference in stiffness between the two materials seems too important for Abaqus to provide consistent results.

I talked with my supervisor and we did not manage to solve the problem. I will only focus on elastic strain now.
I will try your suggestion and tell you if it works.

Thank you very much for your time.

 

[Emile Pantaleao]

With 1 or 2 rows of elements in the adhesive, the results are far more consistent and compute for higher displacements/strains.

This can be useful if you are interested in load/displacement or stress/strain curves.
In my case it is a good tool to validate the material properties but not for stress repartition in the adhesive layers.

Thank you for the advice.

 

[rb1957]

would a shear lag analysis of the adhesive be appropriate ? at least at the elastic level.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.