Moldflow Insight Forum
Welcome to Autodesk’s Moldflow Insight Forums. Share your knowledge, ask questions, and explore popular Moldflow Insight topics.
cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

Why tria/tetra element types ONLY used in moldflow analysis?

11 REPLIES 11
Reply
Message 1 of 12
rmathan
2440 Views, 11 Replies

Why tria/tetra element types ONLY used in moldflow analysis?

Hello,

 

I have a basic moldflow analysis query.

 

While performing moldflow analysis we use triangular / tetrahedral type mesh for analysis. Why these element types only used and why don't we use other element types?

 

Regards,

Mathankumar.R

11 REPLIES 11
Message 2 of 12
madhukeshwart
in reply to: rmathan

solver algorithems are  developed for these type of mesh to do calucalations in moldflow

 

so we need to use these types only.

Madhukeshwar Talwar

FORD MOTORS PRIVATE LIMITED, Chennai
mail: madhukeshwart@gmail.com
09600060862
======================================
Please use . Accept as Solution and Give Kudos as appropriate to further enhance these forums. Thank you! .....
Message 3 of 12
rmathan
in reply to: madhukeshwart

Madhu,

 

Thanks for your reply.

 

Do you know the basic behind why the solver Algorithams have been developed for these tria/tetra mesh types?.

 

 

Regards,

Mathankumar.R

 

 

Message 4 of 12
birajlahkar
in reply to: rmathan

Because tria and tetra only can give most diminished close loop than other elements (!)

Message 5 of 12
rmathan
in reply to: birajlahkar

Thanks for your reply.

 

Do you know the mathematical calculations or theory behind the tria/tetra mesh used in moldflow analysis?

 

 

Regards,

Mathankumar.R

Message 6 of 12
WarpGuru
in reply to: rmathan

Hi,

 

Are you really sure you want to know the Theory behind? There are excellent books on the subject.

As an example, "The Finite Element Method" by Zienkiewicz and Taylor.

 

Personally, I will say that when it comes to meshing, the best type of element to cover all shapes are tetrahedron in 3D. In addition, they are less inclined to locking phenomena compared to wedges and hexahedron and you can always extract tetrahedron from wedges and hexahedron and not the other way around. 

 

Cheers,

 

WARNING: The above comments are based on personal opinion and should be considered as such with no garantee attached.

Message 7 of 12
sadashivpimple
in reply to: rmathan

are you asking because u have seen sigmasoft and Moldex are using Hexa mesh?

 

there are very nice books avaible to read the maths behind flow analysis and why moldflow used tetra as 3D mesh

 

 

Message 8 of 12
madhukeshwart
in reply to: rmathan

sadasive,


can you please name those book/ authour name???
Madhukeshwar Talwar

FORD MOTORS PRIVATE LIMITED, Chennai
mail: madhukeshwart@gmail.com
09600060862
======================================
Please use . Accept as Solution and Give Kudos as appropriate to further enhance these forums. Thank you! .....
Message 9 of 12
sdpimple
in reply to: madhukeshwart

Flow analysis of injection molds:Peter Kennedy
 
Injection Molding: Integration of Theory and Modeling Methods By Rong Zheng
Message 10 of 12
rmathan
in reply to: sdpimple

Thanks!

 

Regards,

Mathankumar. R

Message 11 of 12
prakashcheyyar
in reply to: rmathan

Most of the geometries we encounter are way too complex for HEX meshing in 3D solid elements (different wall thickneses, crazy curved surfaces etc.), what I am trying to understand is how critical is it really? Today with advanced CAD tools, design engineers are creating crazy geometries since it is possible in the CAD tool and also in the advanced manufacturing methods and HEX meshing seems unfeasable in lot of cases.

 

Hexahedron is always better than tetrahedron.

Most old text books will tell you hexa (quad) mesh is better than tetra (tri) and show you how larger the numerical errors may be introduced by tetra (tri) mesh. Sometimes, this is true, especially 15 or 20 years ago.

Historically, people prefer hex mesh due to: 1). at that time, only structured mesh can be used for most CFD solvers ; 2). less element count (so, a lot of saving in RAM and CPU time); 3). unstructured solver was not matured.

The solver technology developments in most commercial FEA codes in last decade have led to the similar results for hex and tetra mesh for most problems . Of course, tetra mesh normally need more computing resources during solving stage. But this can be easily offset by the time saved in mesh generation. The accuracy advantage of hex mesh is no longer existing anymore, for most engineering problems.

For some special applications, e.g., wind turbine, pump, or airplane, hex mesh is still preferred, because of 1). industry convention; 2). well-understood physics (most users know how to align the mesh); 3). special tools to generated hex mesh for such geometries.

However, for most FEA and CFD users, if the geometry is slightly complicated, it is just a waste to spend time on hex meshing. Your results will not be better, most of time, if not always. The (solver) computing time saved with hex mesh is marginal compared with time wasted in mesh generation.

______________________________________________________________

If my post answers your question, please click the "Accept as Solution" button. This helps everyone find answers more quickly!
Message 12 of 12

ok have you guys checked or comparied the Tetra 10 layer with 5BLM and Hexa runner mesh results ?

Can't find what you're looking for? Ask the community or share your knowledge.

Post to forums  

Autodesk Design & Make Report