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dkosheba
Posts: 2
Registered: ‎11-05-2012

Mesh pattern related to Warpage Accuracy?

782 Views, 6 Replies
11-05-2012 01:51 PM

Is there any study that concludes the mesh needs to be random in pattern and not highly aligned on surface to provide a better warpage solution? 

 

Using Moldflow to mesh CAD generates a random tria pattern which I was told is good to provide a more stable solution.  The flip side are highly aligned mesh from third party software that looks like a very structured quad mesh, and then split to trias. All of the elements are aligned in rows based on the geometry of the part, and look very neat.

 

The reason I ask, I have part that was meshed very neat and the warpage prediction is wrong.  I then mesh the native CAD in Moldflow and the warpage prediction is correct on direction now, and only off on magnitude.  This is the same on the Dual domain part, and 3d meshed part.  

 

I suspect the high alignment of elements in rows is causing a problem in performing the structural analysis aspect on warpage, and with the trias aligned, it can artificially bend on the rows of nodes, and in this case, the wrong direction.

 

Don K.

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Active Member
jim.mcguire
Posts: 8
Registered: ‎12-22-2009

Re: Mesh pattern related to Warpage Accuracy?

11-07-2012 10:20 AM in reply to: dkosheba

Don,

 

This is an important question, and one I'm surprised that no Autodesk personnel have attempted to answer.  We can all explore this, but I think that Autodesk should give us a definitive "best practice" guideline for this.

 

Could this be a case in which large deflection 3D analysis should be used?  If the answer is so sensitive to mesh, perhaps that is why. 

 

Very best regards,

 

Jim McGuire

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Mentor
madhukeshwart
Posts: 263
Registered: ‎03-18-2009

Re: Mesh pattern related to Warpage Accuracy?

12-27-2012 05:38 AM in reply to: dkosheba
yes...Right angle tria elments ( i.e create quad elements first and then split them in to two tria element, which create two right angle tria elements) are not preferrable for structural analysis/ i.e warpage analysis.

.But moldow tech team never ever commented on that to support this comment.

I may be wrong.. If they say same.
Madhukeshwar Talwar
FIAT-CHRYSLER ATC, Chennai
mail: madhukeshwart@gmail.com
09600060862
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madhukeshwart
Posts: 263
Registered: ‎03-18-2009

Re: Mesh pattern related to Warpage Accuracy?

12-27-2012 05:43 AM in reply to: dkosheba
I.e equilateral triangles are preferred......
Madhukeshwar Talwar
FIAT-CHRYSLER ATC, Chennai
mail: madhukeshwart@gmail.com
09600060862
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madhukeshwart
Posts: 263
Registered: ‎03-18-2009

Re: Mesh pattern related to Warpage Accuracy?

07-03-2013 11:17 PM in reply to: madhukeshwart

 

why right angled tria elements are not preferred in moldflow and why equilateral traingles are preferred?

 

Is there any one can answer and explain the theory behind this ?

Madhukeshwar Talwar
FIAT-CHRYSLER ATC, Chennai
mail: madhukeshwart@gmail.com
09600060862
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madhukeshwart
Posts: 263
Registered: ‎03-18-2009

Re: Mesh pattern related to Warpage Accuracy?

07-04-2013 04:05 AM in reply to: madhukeshwart

why right angled tria elements are not preferred in moldflow and why equilateral traingles are preferred?

Is there any one can answer and explain the theory behind this ?

 

refer attached image

Madhukeshwar Talwar
FIAT-CHRYSLER ATC, Chennai
mail: madhukeshwart@gmail.com
09600060862
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madhukeshwart
Posts: 263
Registered: ‎03-18-2009

Re: Mesh pattern related to Warpage Accuracy?

07-08-2013 11:17 PM in reply to: dkosheba

The aspect ratio of mesh elements can affect analysis performance. High aspect ratios can cause a slower analysis, and affect results.

In right angled traingles, with the longest side in the direction of flow, the end node of high aspect ratio elements will add an excessive resistance factor to flow front calculations.

we need to avoid very high aspect ratio triangles, which have their longest side in the direction of flow.

If very high aspect ratios cannot be avoided, the longest side should, if possible, be at right angles to the flow direction.

Probably moldflow recommended aspect ratio < 6 will take care the same.

Madhukeshwar Talwar
FIAT-CHRYSLER ATC, Chennai
mail: madhukeshwart@gmail.com
09600060862
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