I am using cohesive contact in abaqus,

I plot the variable CPRESS (contact pressure) along a path (undeformed) of neighbouring nodes.

I plot the stress components (S11, S12, S22, et cetera) along the same path (undeformed).

Then, I project the stress tensor along the normal direction (meaning I calculate n * sigma * n), where * is the scalar product, sigma is the stress tensor (using S11, S12, S22, et cetera)

and n is the undeformed surface normal.

When I plot the Abaqus CPRESS and calculated CPRESS along the path,

they are of course correlated, but I always find a mismatch (about 10%).

How does Abaqus calculate CPRESS?

Is there a relationship with the stress tensor at the nodes?

Is there a relationship with the stress tensor at the integration points?