Hex Mesh or Second Order Tet mesh ?

[mvg1982]

For any given analysis I see that most people end up choosing Hex mesh but why not second order Tet mesh ?

I know some of the advantages of Hex over Second order Tet-

1. For a given model the hex elements would produce lesser number of elemnts than the tetrahedron elements.

2. Number of equations will be lesser and hence computations are quicker.

But tet mesh can engulf the geometry in a best way than hex.

Is there any reason why preference of hex is over tet ?

 

[rstupplebeen]

Solve time for a given model accuracy is better with Hex. Tet always (usually?) less user intervention. It is a quick cost benefit for me. Sometimes I save my time at the expense of the computer's.

Rob Stupplebeen

 

[BlasMolero]

Hello!,
Nothing to see Hex elements with Tetra elements, if the geometry is suitable to mesh with 3D solid brick HEX elements, do it, the accuracy of the solution is times what you get with Tetra elements. CHEXA(8) gives better mesh quality & accuracy of results than CTETRA(10), and depending the problem the use of HEX elements is critical, for instance highly nonlinear with contact, geometry & material problems (for instance, hiperelastic materials)where the use of high-order CHEXA(20) and better CHEXA(27) "u/p" elements with mixing interpolation.

The main advantage of CETRA(10) elements is simply the easy to mesh any geometry, but you will pay a price: the accuracy of the solution. Then, depeding of the problems's geometry, if it can be simplified in order to mesh with HEX elements I will spend the time required to mesh with CHEXA(8) elements, of course!!.
Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48011 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

 

[gwolf2]

mvg1982,

I think you have answered your own question in the post. You have already identified the main reasons. I suggest you go play around with some small test models and look at averaged nodal, unaveraged nodal and integration point stresses around a fillet using TET and HEX8/20 and varying numbers of elements around the curve and though the thickness. This will show you what is going on and guide all of your future meshes. Any analyst worth their salt has been through this process.

gwolf2