Hex vs Tets
Hex vs Tets
(OP)
I am a newbie analyst looking to gather the opinion of this great forum. When using solid elements I have been mainly sticking with hex elements, but with some added complexities to my current project’s design I have been leaning towards using tets with midside nodes. What is everyone’s take on hex vs tets? Are there some general issues to watch out for when using tets?
Thank you in advance!
Thank you in advance!





RE: Hex vs Tets
I'm an intermediate level analyst so the advice I offer may be trumped or further refined by the many here which have more experience than I.
One thing about tet meshes is that you will typically end up with a model that has significantly more DOF's than you would with a hand built hex mesh. This is something that you'll want to keep in mind when you have a project which may push the limits of your computational resources (whatever they may be).
There is no reason why second order tets shouldn't produce what you consider to be acceptable results with the appropriate mesh. As with anything new you will want to err on the side of caution, test analytical solutions against experimental and theoretical solutions, and refine your mesh to the point where you see a mesh convergence in your models. Over time you'll gain the first hand knowledge of what is or isn't a satisfactory mesh for your application.
Hope this helps,
-Brian
RE: Hex vs Tets
There are plenty of analysts about who still insist on hex meshing everything, but with the abundance of available CAD geometry they are a dying breed.
RE: Hex vs Tets
Also in practice, you can just as easily goof up the analysis with hex meshes as with tet meshes.
RE: Hex vs Tets
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Hex vs Tets
When working with a situation where the stresses are mainly from bending, is there a rule of thumb for the number of tets a long the thickness? For hex elements I've heard at least four should be used.
Thanks again!
RE: Hex vs Tets
For dynamics and stiffness then you can be a lot more casual about element quality, the most important thing is to get the mass right and make sure the mechanisms and bcs are OK.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.