helppyFormex - Support: sr #110495, beam section orientation (for...


sr #110495: beam section orientation (for abaqus)

Submitter:  Annika Holzschuh <annika>
Submitted:  Thu 20 May 2021 10:06:29 AM UTC
Category:  None Priority:  5 - Normal
Severity:  3 - Normal Privacy:  Public
Assigned to:  None Open/Closed:  Open
Operating System:  GNU/Linux
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Fri 28 May 2021 11:56:00 AM UTC, comment #3: 


Indeed, that shouldn't make a difference.

Benedict Verhegghe <bverheg>
Project Administrator
Fri 28 May 2021 11:13:31 AM UTC, comment #2: 

Hi Benedict,

Thank you for your answer and the insight into your inp file.
So I guess the positive or negative direction of the beam orientation shouldn´t make any difference. 


Annika Holzschuh <annika>
Wed 26 May 2021 07:57:41 AM UTC, comment #1: 

Hi Annika,

The material data for the beam elements should be specified in local axes, with one axis being along the wire element. And if the wires are circular (what I expect), there is no need to specify the orientation of the cross axes. I has a look at some old .inp files (generated by our pyFormex scripts from just specifying the wire diameter and material params) and found the following section definition:

0.0176714586764, 2.48504887637e-05, 0.0, 2.48504887637e-05, 4.97009775275e-05

2.060000e+05, 8.150000e+04

The first line would be the area, moments of inertia and torsional constant of the cross section; the third line is the E, G of the material.

If you have flat wires, something could be added to the script export the local directions at each point.


Benedict Verhegghe <bverheg>
Project Administrator
Thu 20 May 2021 10:06:29 AM UTC, original submission:  


I am using pyformex to create an input file for abaqus, containing mesh with node and element sets, element type, Profile for B31 elements and material data. Further Model input is generated in a py script. The purpose is to simulate the mechanical behaviour of a stent (with looped ends).
When compressing the stent radially, reaction forces are to low (factor 10). I went through possible bugs in my model. What I am not sure about is the beam section orientation. When creating the geometry and mesh with pyformex and assigning the orientation in abaqus (0.0,0.0,-1.0), the tangent direction flips within the filament. Is there a way to fix that? So is there a way to orienate the tangents along the filament, independent of the unit cells?

I would be grateful for advice.
Best regards, Annika

Annika Holzschuh <annika>


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