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How to avoid meshing problems for a shell model

11 REPLIES 11
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Message 1 of 12
jo2ny
1029 Views, 11 Replies

How to avoid meshing problems for a shell model

Hi,

Just finished a model cosisting of aprox 1300 panels. Two days ago. Since then i'm trying, without success, to mesh it properly.

I tried all types of messhes, coons, delunay, delunay + kang, used kinematic constraints, used iterative, squares fe, triangular fe, tried to autocorrect the model, set a less restrictive model tollerance. I'm currently out of options with one week of modeling without the posibility to run the model.

I constantly get incoherent mesh on edges, whatever I do.

I need to specify, that fearing I would end up like this I've drawn the model entirely in Robot, rather than importing it / anything. I knew that importing would increase the risc of this, as it happened before.

So, 2 questions. What could I do to mesh it properly and run it.

Secondly, is there a "recipe" of modeling and/or meshing in a way that everything works fine from the first time (not meshing, remeshin, regenerating computational model, corecticting drawing model etc.) Or maybe some tips, or to-do's or to-don'ts, anything ?

 

Thank you.

 

11 REPLIES 11
Message 2 of 12
Rafal.Gaweda
in reply to: jo2ny

File please


Rafal Gaweda
Message 3 of 12
Rafacascudo
in reply to: jo2ny

When the model is huge and very " confusing"  I use to create nodes for the panel contour points and then , mark "snap to nodes" only. I never mark all snap options at the same time. I add each snap option one at a time as I need it.

 

Also , at some crowdy points(many bars ,panels arriving at a point) , always check the coordinates( I use 4 decimals or more) at the botton status bar.

 

If you are copying or moving panels,bars ,etc, always check the displacement vector. Beware of  -0.0000 or  5,0001  values . If you´re getting this values , probably ,you´re snapping to the wrong point. Increase the zoom and only click to  the point if you know it´s right.



Rafael Medeiros
Robot Structural Analysis

Message 4 of 12
jo2ny
in reply to: jo2ny

File: http://we.tl/cHgVg5GWc2

Thank you for your time!

Message 5 of 12
Rafal.Gaweda
in reply to: jo2ny

Are you playing in the contest how precise FEM model can be made ? 🙂
First of all you need at least 40mm mesh, not 200mm.

So you should get more than 200000FEs generated

We will so over night what will happen. 



Rafal Gaweda
Message 6 of 12
Rafal.Gaweda
in reply to: Rafal.Gaweda

Lucky You 🙂

~100000 FEs only

with the settings below meshing works like a charm :

- no kinematic links

- meshing options as shown below:

 

c6.jpg

 

after meshing add missing rigid links in such places:

 

c61.jpg

 

Meshed model : http://we.tl/0isjEwXoo9

 



Rafal Gaweda
Message 7 of 12
jo2ny
in reply to: Rafal.Gaweda

Many, many thanks! I very much appreciate your time and effort

Over 100k Thanks! 🙂 

 

How did you determinte that 40mm is needed? 

 

Again, many thanks!

 

 

 

Message 8 of 12
Rafal.Gaweda
in reply to: jo2ny

See below, additional remark on screen shot

 

c62.jpg



Rafal Gaweda
Message 9 of 12
jo2ny
in reply to: Rafal.Gaweda

Ok, so for future modeling of this type, mesh element size would be equal to the smallest side of panel.

Yes for the rigid links. I intended to add them after meshing, to be shure i get all points of the shells edges near each bar end node.

 

Thank you!

 

Message 10 of 12
Rafal.Gaweda
in reply to: jo2ny


Ok, so for future modeling of this type, mesh element size would be equal to the smallest side of panel.

 

More less.

The smallest is half of I section flange, I guess , but correct FEs wil be generated there by forcing divisions on flanges by web panels.



Rafal Gaweda
Message 11 of 12
anthonymctigue
in reply to: jo2ny

I too am having difficulty with applying mesh to a trial model I am building in Robot (see attached screenshots).  As you can see, for some bizzare reason, the mesh on one of my walls does not mesh in the plane of the wall but rather follows some bizzare arched pattern?  I tried using the meshing options suggested above but some of the settings are greyed out and cannot be changed.?

 

Regards,

Anthony McTigue

FMG Engineering

Level 1/2 Domville Avenue,

Hawthorn, VIC 3122

Message 12 of 12

Please disregard my previous post.  I noticed I had not selected Delaunay properly.  I deleted the troublesome wall and it is meshing properly now.

 

Regards,

Anthony McTigue

FMG Engineering

Level 1/2 Domville Avenue,

Hawthorn, VIC 3122

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