Hello,
I am building a 2D textile using the CTextileWeave2D() function in Python. The yarn/textile geometry inputs I am using for this function are:
1. number of weft yarns: 2
2. number of warp yarns: 2
3. yarn spacing: 0.225
4. layer height: 0.1 (target yarn thickness 0.05)
After this, I set the yarn width and height to be:
yarn width: 0.1
yarn height: 0.05
I assign the default domain and then render the textile. Before I save the textile, I use the DetectInterference() function and there are no interferences. However, after I save and open the textile again 12 interferences appear.
Even if I run the automatic correct interferences algorithm in the GUI it is not able to fix the overlap. This is causing some troubles for me when I try to export as a STEP file to GMSH because the geometry is overlapping. Could you please help me figure out how to fix these interferences?
I tried to add a vertical gap with the SetGapSize() function and it corrects the interferences in TexGen but then GMSH has problems meshing.
Thanks for the help.
Yarn Intersections After Saving Textile
Moderators: Martin, Developers
Re: Yarn Intersections After Saving Textile
Hi,
I have followed the procedure that you gave. If you use the Render Textile Interference Depth function you will see that there are 12 intersections but that the maximum depth is 6.87e-18 so I think that this is just a floating point, computational error. To all intents and purposes there is no intersection. I checked in the STP Viewer and the export seems to be fine. If you manage to export with no intersection and then GMSH crashes it would seem that there is a problem with that rather than TexGen. I'm afraid I haven't used it myself.
Is there a reason that you are meshing externally and not using one of the meshing options in TexGen? If you export as a STEP then you only export the geometry and lose any orientation and Vf information. Also, are you meshing just the yarns or the domain (ie the matrix) as well? If you're meshing both then this may be what is crashing GMSH as it may not be able to cope with the small areas where the yarns meet. tetgen also crashes in this case for the same reason. This is the difficulty of meshing textile composites!
Hope that helps,
Louise
I have followed the procedure that you gave. If you use the Render Textile Interference Depth function you will see that there are 12 intersections but that the maximum depth is 6.87e-18 so I think that this is just a floating point, computational error. To all intents and purposes there is no intersection. I checked in the STP Viewer and the export seems to be fine. If you manage to export with no intersection and then GMSH crashes it would seem that there is a problem with that rather than TexGen. I'm afraid I haven't used it myself.
Is there a reason that you are meshing externally and not using one of the meshing options in TexGen? If you export as a STEP then you only export the geometry and lose any orientation and Vf information. Also, are you meshing just the yarns or the domain (ie the matrix) as well? If you're meshing both then this may be what is crashing GMSH as it may not be able to cope with the small areas where the yarns meet. tetgen also crashes in this case for the same reason. This is the difficulty of meshing textile composites!
Hope that helps,
Louise
-
seansquares
- Posts: 3
- Joined: Wed Sep 28, 2022 10:03 pm
Re: Yarn Intersections After Saving Textile
Hi Louise,
Thanks for the reply. I am meshing externally because I need to insert pores and cracks into the RVE. I would also like to do some mesh refinement around the yarns and pores to capture any stress concentrations, but it seems like the TexGen volume mesh generates a relatively constant element size. Is there any way to do local mesh refinement and insert pores in TexGen?
For the pores, the only way I can think of is by inserting a yarn with variable cross sectional area.
For mesh refinement, I don't really know what to do because it seems like there is only a single seed size.
I am meshing the domain/matrix region as well. As you said, I think that GMSH has problems meshing the gaps because it will mesh if I specify a super small element size (it takes a while but it works). TexGen's Merge Tolerance in the volume mesh is particularly useful for overcoming this problem. However, GMSH makes it much easier to insert pores and perform mesh refinement so I'm currently trying to weigh the tradeoffs associated with meshing directly in TexGen and exporting to GMSH.
As far as the orientations, I have been using the script provided in another forum post (see link below) to recover the orientations after exporting an ABAQUS input file from GMSH.
Define Orientation Script: https://github.com/louisepb/TexGenScrip ... ntation.py
Thanks,
Sean Skweres
Thanks for the reply. I am meshing externally because I need to insert pores and cracks into the RVE. I would also like to do some mesh refinement around the yarns and pores to capture any stress concentrations, but it seems like the TexGen volume mesh generates a relatively constant element size. Is there any way to do local mesh refinement and insert pores in TexGen?
For the pores, the only way I can think of is by inserting a yarn with variable cross sectional area.
For mesh refinement, I don't really know what to do because it seems like there is only a single seed size.
I am meshing the domain/matrix region as well. As you said, I think that GMSH has problems meshing the gaps because it will mesh if I specify a super small element size (it takes a while but it works). TexGen's Merge Tolerance in the volume mesh is particularly useful for overcoming this problem. However, GMSH makes it much easier to insert pores and perform mesh refinement so I'm currently trying to weigh the tradeoffs associated with meshing directly in TexGen and exporting to GMSH.
As far as the orientations, I have been using the script provided in another forum post (see link below) to recover the orientations after exporting an ABAQUS input file from GMSH.
Define Orientation Script: https://github.com/louisepb/TexGenScrip ... ntation.py
Thanks,
Sean Skweres
Re: Yarn Intersections After Saving Textile
Hi Sean,
There is now an octree refinement and smoothing function which implements refinement around yarn boundaries. It doesn't allow you to specify where refinement takes place so if that's what you're after then it probably won't work for you. There is information on its use in the scripting guide here: https://github.com/louisepb/TexGenScriptingGuide
There isn't a way of inserting pores within TexGen. I think that your suggestion of inserting a yarn with variable cross section is probably the most straightforward.
Best wishes,
Louise
There is now an octree refinement and smoothing function which implements refinement around yarn boundaries. It doesn't allow you to specify where refinement takes place so if that's what you're after then it probably won't work for you. There is information on its use in the scripting guide here: https://github.com/louisepb/TexGenScriptingGuide
There isn't a way of inserting pores within TexGen. I think that your suggestion of inserting a yarn with variable cross section is probably the most straightforward.
Best wishes,
Louise