Discussion Groups

Simulation Mechanical and Multiphysics

Reply
Active Member
praveena46
Posts: 10
Registered: ‎06-30-2014
Accepted Solution

Unable to mesh a 2d model imported from Rhino 5

171 Views, 16 Replies
06-30-2014 01:45 AM

Dear All,

 

Hi, I am currently working on an insect wing simulation project, whereby i have enclosed my models for your kind perusal. I have been trying to mesh the models in 2d with little success. It keeps on saying the wireframe does not enclose a single area. I would like to simulate my wing in a flapping motion and I have no idea what went wrong. I created my model in Rhino 5 and imported it as a .dwg model because .iges and .stp failed. Could you please suggest an alternate option to help me with my project? Please help. I have changed the plane into YZ and nothing seems to work. If I have to re-create my drawing do let me know as well. Thanks

Please use plain text.
Valued Mentor
AstroJohnPE
Posts: 503
Registered: ‎08-30-2012

Re: Unable to mesh a 2d model imported from Rhino 5

06-30-2014 08:40 AM in reply to: praveena46

According to the Help documentation, each region that you want to mesh needs to be on a different part number. In the cidada drawing, I count up 18 different regions. Therefore, the wing needs to be drawn on 18 different parts. (If you isolate part 1, it will be a complete outline of section 1. Isolate part 2, and it will be a complete outline of a different section. And so on.) Your image shows that everything is in part 1.

 

It is probably the same issue for the dragonfly wing, but there are too many regions for me to count. :smileyhappy:

 

But before you go to the trouble of creating 18 complete parts, I am curious to know

  1. what are the details of your analysis? (analysis type, element type, loads, constraints, etc)
  2. is it really necessary to have the mesh follow the pattern you have drawn? If so, why?

 cicada.jpg

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

16 years experience with Simulation Mechanical
Please use plain text.
Active Member
praveena46
Posts: 10
Registered: ‎06-30-2014

Re: Unable to mesh a 2d model imported from Rhino 5

07-02-2014 01:51 AM in reply to: AstroJohnPE
Mr. John,

I am finally able to mesh my cicada model and currently working with the analysis report. The trouble is still with my dragonfly wing, I am planning to work on a static analysis. Element would be 2D and the BC would be at the root of the wing, a concentrated force on the edge of the wing. Perhaps I do not need to mesh the whole model as you had suggested...only the tip and the root would do. Yet when I have imported my model from Rhino to Autodesk, my polylines are recognized as different vertices...and I have no idea on how to combine them into one...also if i create a 2d mesh, it is not able to mesh the whole part maybe due to the complexity. How do I separate parts? Will it not be possible for me to choose to mesh only the root and the edge of the wing and look at the changes?


Hoping very much for your reply, my due date is nearing and I am in a panic state at the moment.

Thanks and God Bless
Please use plain text.
Valued Mentor
AstroJohnPE
Posts: 503
Registered: ‎08-30-2012

Re: Unable to mesh a 2d model imported from Rhino 5

07-02-2014 09:19 AM in reply to: praveena46

Sorry if my question 2 was not clear. I was not suggesting to mesh a limited portion of the wing ("only the tip and the root would do"). I am suggesting that you mesh the entire wing. But instead of using 18 parts for the cicada wing so that the final meshed model looks like this (where each color and number represents a different part):

 

cicada2.jpg

 

I am suggesting that you make the entire wing one part so that it looks like this:

 

cicada1.jpg

 

Delete all of the interior lines from the wireframe and just leave the outline. This will give you a mesh of the entire wing. Of course, the random mesh does not follow the 18 regions, so my question was intended to be "does the mesh need to follow the 18 regions"?

 

To fix the problems with the imported wireframe, you can use the commands on the "Draw" menu -- assuming that you cannot fix them in the original drawing or by changing the "Tolerance" on the "2-D Mesh Generation" dialog. You may need to draw lines in Simulation Mechanical to connect the endpoints that are not connected together, or trim off a portion of the existing wireframe and replace it with a longer line or arc or spline.

 

If you want some practice with drawing, you can use either of these documents:

  • the tutorial titled "2-D Weldment Model" located in the "Start & Learn > Learn > Tutorials"
  • the page titled "Water-Cooled Wall with Radiation, Convection, and Temperature Model" located in the "Start & Learn > Learn > Help > User's Guide > Examples > Modeling" section of the help documentation.

 

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

16 years experience with Simulation Mechanical
Please use plain text.
Active Member
praveena46
Posts: 10
Registered: ‎06-30-2014

Re: Unable to mesh a 2d model imported from Rhino 5

07-06-2014 10:47 PM in reply to: AstroJohnPE

Hello John,

 

 Thank you for your response and I am glad to have someone to assist me. I am finally able to mesh both my models using a 2d mesh...I have created the hindwing of the dragonfly as well and now it is facing the same problem. The error message is just that the mesh could not be generated succesfully. Previously, after doing many modifications, the mesh was created after refining the mesh size. For the model that I have created now, what do you think would be the suitable geometric ratio, layer factor, angle, density and so on. I would like to use mixed elements for my meshing purpose. I have attached my wing model for your perusal. Please do have a look.

Please use plain text.
Valued Mentor
AstroJohnPE
Posts: 503
Registered: ‎08-30-2012

Re: Unable to mesh a 2d model imported from Rhino 5

07-07-2014 05:58 AM in reply to: praveena46

Why are you using so many regions in the model? How do the regions affect the engineering or analysis?

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

16 years experience with Simulation Mechanical
Please use plain text.
Active Contributor
txfingenieria
Posts: 29
Registered: ‎04-08-2014

Re: Unable to mesh a 2d model imported from Rhino 5

07-07-2014 12:53 PM in reply to: praveena46

Hello

 

The question is are you going to assign different thickness to each area?

If i understand correctly the image of the dragon you are going to have two different thickness, the thickness of the wind skeleton or frame and the thickness of the area between the frame. am I correct?

 

 I transfer the model to my autocad 2015 and i didnt get the areas, only lines, I created the areas for each zone , I make a substract boolean operation and get 901 parts I checked in my Autodesk simulation and the model is working. I leave you the autocad file each area as an element.

Please use plain text.
Active Contributor
txfingenieria
Posts: 29
Registered: ‎04-08-2014

Re: Unable to mesh a 2d model imported from Rhino 5

07-08-2014 06:16 AM in reply to: txfingenieria

This is the result of the mesh

Wind.jpg

Please use plain text.
Active Member
praveena46
Posts: 10
Registered: ‎06-30-2014

Re: Unable to mesh a 2d model imported from Rhino 5

07-08-2014 08:19 AM in reply to: txfingenieria

Thank you very very much....I shall try this in autocad 2015...i have never used autocad 2015 before...only rhino...i have no idea on how to do it in autocad 2015.... looking at your mesh i guess my earlier wings was not meshed properly...i am truly grateful for your help...shall try this and find out how can this be done....by the way...what element did u used to mesh the model...is it 2d?

 

 

Thank you very much and you have saved my day....god bless u..thanks again...do keep in touch please as i need to try it out and get back to u if i face any complications....

Please use plain text.
Active Contributor
txfingenieria
Posts: 29
Registered: ‎04-08-2014

Re: Unable to mesh a 2d model imported from Rhino 5

07-08-2014 11:39 AM in reply to: praveena46
Yes I used a shell element/plate element.
Please use plain text.