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2d Polygon Meshing Algorithm References

2d Polygon Meshing Algorithm References

(OP)
I am looking for a good text book/resource on finite element meshing algorithms. If you have any experience in this realm, I would appreciate some guidance on potential pitfalls/things to look out for regarding these algorithms.

Ideally the algorithm would be able to accommodate 2-d polygons with the potential for polygon holes.

Routes I am investigating

Route 1 - Create internal points within the polygon and use Delaunay triangulation to make the finite elements

Route 2 - Advanced front method

Images from this site:
https://www.pre-scient.com/knowledge-center/produc...'elements.

More algorithms can be found in this document:

S&T - www.re-tug.com

RE: 2d Polygon Meshing Algorithm References

I’ve almost bought this one, based on title alone, on several occasions: Link (I’m personally a long way off from learning the meshing side of it)

Try asking this in the FEM channel instead you’re likely to get more hits for this topic there.

I'm making a thing: www.thestructuraltoolbox.com
(It's no Kootware and it will probably break but it's alive!)

RE: 2d Polygon Meshing Algorithm References

I'm making a thing: www.thestructuraltoolbox.com
(It's no Kootware and it will probably break but it's alive!)

RE: 2d Polygon Meshing Algorithm References

The Professor on Degree Tutors is using Blender to create the mesh in some of the tools he has created. Blender Mesh Blender is opensource. This may not be what you are looking for, but I thought I would mention it.

I am always impressed how some of you find time for these type of projects.

RE: 2d Polygon Meshing Algorithm References

Plenty of time to hoard books and pdfs on the subjects, but no time to actually process them though. Work has ramped up significantly and my kid just hit the terrible 2's and a bit of sleep regression.

I'm making a thing: www.thestructuraltoolbox.com
(It's no Kootware and it will probably break but it's alive!)

RE: 2d Polygon Meshing Algorithm References

(OP)
Celt, thanks for the book reference, looks like a good one.
Brad, thanks for the blender recommendation, that was one that was not on my watch list. Looks promising, has a python API.

I've got a lot of free time right now as my wife works way more hours than me, no kids and there is no snow falling yet.

S&T - www.re-tug.com

RE: 2d Polygon Meshing Algorithm References

If you are looking for a robust and fast implementation for python, this library is a python implementation of the popular and free meshing library triangle. There are lots of options for constraining mesh size and quality.

RE: 2d Polygon Meshing Algorithm References

(OP)
Thanks handofthelion, I saw that you use triangle in section properties and concrete section properties python package.

@Celt, I have not played around much with getting python package to run on the web, would you mind explaining the process of implementing the triangle python package on a website.
Do I download the triangle library and serve it up to my static directory?

Thanks!

S&T - www.re-tug.com

RE: 2d Polygon Meshing Algorithm References

are you using django for your backend?

My understanding is you don't run the python package via the web but instead need to create a link from the front facing html to a back end api.

For me with Flask I install the python package via pip on the server then make sure I can access it with a small test console app. On the flask end I pull user input via an HTML request and run the python package on the server side and send back results to be rendered. Check out how I did the steel database that one uses javascript to send data to a specific address that flask grabs, processes, and then returns a block of json data to be further processed with javascript and then inserted into the front facing web page.

I'm making a thing: www.thestructuraltoolbox.com
(It's no Kootware and it will probably break but it's alive!)

RE: 2d Polygon Meshing Algorithm References

(OP)
Yep, using django for the backend.
Thanks for the write up on Flask, I believe the process is the same on thank Django side.

All of the passing of data sounds complicated, so I am trying to keep it purely javascript.
I made good progress over the weekend using the ray caster algorithm, brute force point generation and delaunay triangulation.

Now onto concrete design stuff.

S&T - www.re-tug.com

RE: 2d Polygon Meshing Algorithm References

Nice! that's pretty slick.

I'm making a thing: www.thestructuraltoolbox.com
(It's no Kootware and it will probably break but it's alive!)

RE: 2d Polygon Meshing Algorithm References

I found this searching for code ideas today, and I thought you might be interested. Centric Engineers 2D

RE: 2d Polygon Meshing Algorithm References

I thought the XCross2D output at the CentricEngineers link looked suspiciously similar to the sectionproperties output, but then I read:

"Thanks to the team at sectionproperties who made it possible to bring this functionality to CentricEngineers.com in record time and make it freely available to our users!"

So that's OK.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

RE: 2d Polygon Meshing Algorithm References

The beam tool they have is also based on an open source package on Github, Symbeam. They gave them credit for that one as well. That was the one that led me to the site

RE: 2d Polygon Meshing Algorithm References

(OP)
Interesting, Centric Engineers built a web based UI around some of these more famous open source packages.

Very cool, I kinda wanted to do that for sectionproperties myself, I will have to try it out.

S&T - www.re-tug.com

RE: 2d Polygon Meshing Algorithm References

I like the science behind computation geometry, but from a structural engineers perspective nothing compares to square/rectangular quads with internal angles close to 90 degrees. Very hard to do. I haven't really followed any science behind the meshing in my programs for mesh generation, but in doing so it really loses much of the general purpose functionality.

RE: 2d Polygon Meshing Algorithm References

Quote (sticksandtriangles)

Very cool, I kinda wanted to do that for sectionproperties myself, I will have to try it out.

My Excel interface for sectionproperties has open source Python code, so you are free to use that if it is helpful (or use the spreadsheet without coding via the pyxll add-in).

See:
https://newtonexcelbach.com/2022/01/16/sectionprop...

and following posts

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

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