Abaqus / polymer / simulation

Hi all,

I'm trying to model a peel T test on a composite material composed of steel and polymer (polypropylen) on Abaqus 6.7. Between these parts, there are cohesive elements COH3D8.
I have a problem with my model and I don't understand it. You can visualize my results in attachs files.
For understand this draw, a few precisions:
The elements in white has just here to guide the materials.
In B (cf attachs files), the nodes are embedded.
In A I applied a velocity.
In C I applied rotation constraints and coupling constraints on all rotations and displacements.
My structure present a strange evolution in the red circle. I don't understand this.

Have you an idea on what is happened in my structure? It is a problem of material? Maybe you have had the same problem...
If you need more precision on the model, the materials or limits conditions, I'll answer it of course.

I have too a problem of element distortion. It was a link between these things?

Excuse my poor english.
Poucinette