Strange cohesive element behavious (abaqus)

[loki3000]

how is it possible that i get compression in cohesive elements of a part that has a single tension force (and one boundary -- a cylinder) applied. most of the cohesive elements (COH3D6) that have (s33) values negative, have a normal perpendicular to the acting force.
there are no probs. with mesh, it's ok and values are also positive for the most part except for the local minimi. denser mesh also makes no difference.

unfortunately i can't attach an odb, as it's >1gb.

 

[sartorbjk]

Your tension stress, is it distributed on the surface that you are applying? or is it a single force at one node?

Can you upload CAE file?

 

[rodneybennet]

Do you have temperature or mass diffusion gradients applied?
This could give rise to (additional) forces, and - in a cylinder configuration - to compressive forces. Check also the integrated diffusion-chemical-mechanical composites simulation at

http://www.composite-agency.com/materials-forum.htm

Regards,
Rodney