Cohesive element-Top and bottom surface

[Rizviul]

Dear Kristoffer,
Thank you for this very nice program. I am using your code with neper to generate cohesive elements for abaqus and finally applying compressive loading. I have observed that the top and bottom surface of the cohesive elements are somewhat random. It makes some inconsistent deformation in cohesive elements during compression loading.
For compressive loading the top and bottom surface of the cohesive elements should be consistent. An improvements can be done by checking the surface normals are within 0-180° orientaion for Top surface and if they are 181-360° for bottom surface. Cohesive element node numbering should be done accordingly.
Is it possbile to modify the node numbering in cohesive elements such that we get top surfaces always between 0-180° and bottom surface between 181-360°.
Thank you in advance.
Rizviul

[KristofferC]

Is the problem that the normal to the cohesive element is pointing the wrong way for some elements? Can you show an image showing the problem.

I compute the normal here:

Phon/phon/mesh_tools/create_cohesive_elements.py

Line 171 in 653aec2

norm_cohes = _calculate_normal(mesh, cohesive_element.vertices, mesh_dimension)

so you can do whatever you want there depending on the normal.

[Rizviul]

Dear Kristoffer,
Sorry for the late reply. Yes, element normal is pointing wrong way. The surface normal defines the top and bottom surface in abaqus. Upward normal is the top surface.
Please see the image about top and bottom surface of the cohesive element (from abaqus cae).
I am checking your code to understand the computation of the normal. Thanks for the suggestion.
Rizviul