Difference between grid and mesh

[salukice]

Hi,

I am currently being trained on the job in FEA and ran into a problem.

I was wondering what the difference between the grid that you set when setting up the analysis and the mesh for a computer model. I always thought the mesh determined the nodes that the values were calculated at but was told here that the grid affects the number of values that are calculated. I was hoping someone could tell me what the difference is between the grid and the mesh.

THANK YOU for your help in advance!

 

[JAE]

It might just be corporate cultural semantics. Also depends on your actual software and the naming conventions it uses.

Not sure we can help here. Usually grid (to me) is the layout of geometric control lines (i.e. column center lines, plate geometry, etc.) that define shape. Mesh usually signifies the actual finite elements themselves.

Sometimes mesh is that wiry stuff that gets stepped on into the mud prior to a slab on grade placement but that's a whole other issue...just venting - sorry.

 

[slickdeals]

Ha ha, JAE.
Don't the contractors say that they usually have a rod buster with a candy cane to place it at the proper elevation when they are placing concrete..........

 

[JAE]

Yes they usually say that.
As they stand on the mesh and try to pull themselves up.

 

[Ron]

JAE...I once asked a concrete finisher who was hooking and pulling up "mesh" in the concrete to take off his concrete boots and untie his regular boots then pull on the strings and lift himself off the ground. He gave me a puzzled look...then started laughing...he figured it out. Didn't stop the process though!

As for the FEA...I have one FEA program that uses both terms. A gross grid is developed to divide the flat section into rectangles or squares. Then meshing can be done on top of that to further refine the finite elements. Most FEA programs that handle plates can mesh/re-mesh/refine, etc. We use RISA 3D for stick analysis, but not for plates. I'll have to try it sometime just to see how it handles things. You're the RISA expert...does it handle meshing/remeshing in the same way as other FEA programs?

I view them as being the same...as you said, just a terminology difference.

 

[msquared48]

To me, grid has always meant two levels of reinforcing at right angles to one another, but not joined or welded together.

Mesh means same as grid, but welded together at the intersections.

Mike McCann
MMC Engineering

 

[BAretired]

I would think that the grid is always orthogonal. Mesh may be of any shape. Could be a bunch of prisms, pyramids, triangles, quadrangles...you name it.

BA

 

[ship4885]

In my experience, the programs I have used will Auto-mesh on your grids or support lines(at beams), and not mesh otherwise unless you specify.
Usually you can additionally mesh your areas based on maximum mesh size or by selecting additional points and lines at which you want to mesh.

What analysis program are you using?