sheared weaves

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NicP
Posts: 2
Joined: Wed Sep 15, 2021 1:58 pm

sheared weaves

Post by NicP »

Dear Dr. Louise and TexGeN community,

I am trying to create a square unit cell with 31 degree braid angle.
However, the fiber bundles always interpenetrate each other, whether I use the wizard or script it myself, even if the yarn spacing should be sufficient.
With increased yarn spacing, the problem is minimized so that the correction algorithm detects the penetrations.
But in this case the fiber volume fraction of the cell is too low.
Attached is a picture of such a cell created with the weave wizard.

The cell is also always created with a sheared Domain. My idea is to export a larger cell (e.g. 6x6 instead of 4x4) and then crop it to a square shape in the pre-processor. Can you think of a better way to do this directly in TexGen?

Thank you in advance
Attachments
picture.JPG
picture.JPG (81.84 KiB) Viewed 9316 times
louisepb
Project Leader
Posts: 998
Joined: Tue Dec 08, 2009 2:27 pm
Location: Nottingham

Re: sheared weaves

Post by louisepb »

Hi,

I think that the issue is probably that the intersection correction algorithm is not so effective at such large shear angles. I wonder if you might get better results if you define cross-sections which are not normal to the yarn (see p21 of the scripting guide here https://github.com/louisepb/TexGenScriptingGuide). I'm not sure how the refinement would work with that though!

The model should only be created with a sheared domain if the box is checked in the wizard. Otherwise the domain should be aligned to the x and y axes. (If this isn't the case you may have found a bug, in which case please report it on GitHub!).

I hope that helps,
Louise
NicP
Posts: 2
Joined: Wed Sep 15, 2021 1:58 pm

Re: sheared weaves

Post by NicP »

Dear Dr. Louise and TexGeN community,

There was probably a misunderstanding. The matrix is only sheared if you select the corresponding box.
In this case, the yarns are aligned parallel to the matrix (image 1).
But the goal is a square matrix with sheared yarns on both sides of the central longitudinal axis (image 2).
The correct fibre orientation, as far as i know, is only possible with a sheared matrix.
My idea so far is to export a larger cell and then cut it to size via ANSA or LSPrepost (image 3).
Can you think of a better way?
The current method is very time consuming and gives an inaccurate unit cell.

Thank you in advance
Attachments
Image3<br />no correct scale, only schematic
Image3
no correct scale, only schematic
Image3.JPG (111.83 KiB) Viewed 9299 times
Image2
Image2
Image2.JPG (89.07 KiB) Viewed 9299 times
Image1
Image1
Image1.JPG (109.04 KiB) Viewed 9299 times
louisepb
Project Leader
Posts: 998
Joined: Tue Dec 08, 2009 2:27 pm
Location: Nottingham

Re: sheared weaves

Post by louisepb »

Hi,

If I understand what you're trying to achieve, you could either rotate the sheared textile and then create a new domain (use the edit domain functions) with sides aligned to the x,y axes or you could leave the textile as it is and create a new domain with faces at the required angles. It propably depends on how you want to have the yarns angled in your model. You will also need to check how the yarn repeats across the selected domain if it is smaller than the unit cell (you will probably need to export without boundary conditions as the domain planes won't match the yarn repeats).

Hope that helps,
Louise
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