Cohesive element/surface non-perpendicular loaded

[StevenJS]

Hi all,

I'm working on a 2D model in Abaqus 6.11.2 with a cohesive surface in it.
This cohesive surface has the shape of a quarter circle.

Due to this shape the cohesive surface is loaded from perpendicular (90 degrees angle) to parallel (0 degrees angle) to the surface.
However the model does not respond as i expected.

After some simple examples i found out that the cohesive surface defenition of mine does give incorrect results when the surface is loaded non-perpendicular.
I also tried adding a cohesive element (with a zero-thickness) instead of a cohesive surface, however this cohesive element also only gives correct results under perpendicular loading conditions.

Can someone please give some advise on the input for cohesive elements/surfaces with non-perpendicular loading?
The input files of my models (with a cohesive element and with a cohesive surface is added).

I'm currently using the following properties for my cohesive surface interaction:

__________________________________________________
** INTERACTION PROPERTIES
**
Surface Interaction, name=Interaction
1.,
*Cohesive Behavior, eligibility=ORIGINAL CONTACTS
0.1, 0.1, 0.1
*Damage Initiation, criterion=QUADS
2.5e-05, 2.5e-05, 2.5e-05.
*Damage Evolution, type=ENERGY, mixed mode behavior=POWER LAW, power=1.
0.0005, 0.0005, 0.0005.
*Damage Stabilization
1e-07
__________________________________________________

The traction-seperation behavior of the cohesive is supposed to look the following: