Need help in meshing a simple plate

I'm having difficulties with the tutorials in trying to do a very simple model. The tutorials are far too complex, and at the same time very cryptic, with little or no explanation of steps taken.

Basically I want to model a 1" by 2" by 0.1" cantilevered plate using 4 by 8 thin shell elements (32 total). The plate is fixed along the 1" length.

The ultimate aim is to get eigenvalues for the first 3 modes.

But the tutorials are so full of complex 3D object manipulations of STEP files of pistons, or hole subtractions and automeshing, etc. That I'm completely lost. Also the shell tutorial is in French, and Babelfish doesn't translate it understandably.

What I've done so far:

I have created the basic 1x2x0.1 box in the Geometry section.

Can someone give me the precise steps to move this to the mesh view and create the mesh?

Once I see that demonstrated, I think I will be able to move on from there. Most of what I want to do is this simple.

Thanks!

Steve

Post edited by: Steve Rednond, at: 2009/10/14 07:00<br /><br />Post edited by: Steve Rednond, at: 2009/10/14 07:03

For getting shell- or plate-elements You must mesh a (rectangular) surface, not a box, because the thickness (0.1) will be assigned later to the elements (and can be varyed without that You recreate Your geometry and Your mesh).

In Salome Geometry Module
Delete Your box. Create a surface (several possiblities, one is to create 4 points, for lines, a wire from the 4 lines, then a face)

In Salome Mesh Module

Mesh - Create Mesh. Select the geometry (your suface). Fill in the 2D- and 1D-mesh-options (Salome creates alway 1D-elements at the contour of Your sufrace and 2D-elements on the surface. The 1D-elm are more basic. Their mesh density determines the 2D-elements' density at the borders of the surface). Apply.

The mesh is created and visible as an object in the obj browser.

It is necessary to have groups within the mesh: Mesh - Create Group. Before You can create them, Your MainShape (Your sufrace) must be exploded. Turn back to the geom module to explode the surface having the border edges. Then again to the mesh module. Create 2 groups, first containing the clamped edge (and its 1D-elm), second to contain the loaded edge. Group names max 8 caracters.

Then go to Salome Aster-Module. Code-Aster-Case - New. You must fill in the mesh (from Your object browser) and a command-file, I attach one here for a lin stat calc with Plate-elm, You must adapt the group-names, good luck!

mit freundlichen Grüßen,

Johannes Ackva

______________________________________________________________________
Ingenieurbüro für Mechanik TRAINING &amp; SUPPORT
Dr.-Ing. Johannes Ackva NASTRAN &amp; CODE-ASTER
Markgrafenstr. 21
D 91717 Wassertrüdingen

www.code-aster.de


(.comm)

Thank you very much Dr. Ackva! <br /><br />Post edited by: Steve Rednond, at: 2009/10/15 06:06

johannes ackva wrote:

Then go to Salome Aster-Module. Code-Aster-Case - New. You must fill in the mesh (from Your object browser) and a command-file, I attach one here for a lin stat calc with Plate-elm, You must adapt the group-names, good luck!

Sorry I didn't specify, but I'm trying to get the first natural frequency eigenvalue for the torsional mode of a cantilevered plate in a dynamic analysis.

Following your very helpful outline of the steps, and using the built in Help system with Salome, I was able to lay out the geometric surface and to create the 4 x 8 quadrilateral mesh. I was able to explode the object and create group for the fixed edge of the cantilever.

I am now ready to specify thickness of the plate, Young's modulus, Poisson Ratio, and mass density (rho), and solve for the eigenvalues of the first three loadcases (modes) for this dynamic analysis of the natural frequencies of this cantilever plate. The torsional mode is the main interest.

Where do I go from here? I cannot find any documentation of how to go about doing this with Code Aster.

I realize that it would be impossible to document the general methods involved, but can someone help with the specific steps to perform only this specific example.

I've attached my .hdf file so far, if that is any help. (I hope it is correct!)

Again, this is a 1&quot; x 2&quot; x 0.1&quot; cantilevered plate, fixed along the 1&quot; edge. Using consistent EE units for the model, the values for Young's modulus is 3e7, Poisson is 0.3, and rho is 7.33e-4.

I just need the steps for setting this up for Code Aster as a plate or shell. I will be able to model similar simple objects once I see how this one was done. Thanks!<br /><br />Post edited by: Steve Rednond, at: 2009/10/15 05:32

Attempted file attachment, unsuccessful, and it won't allow another in an edit. I'll trytryagain...

#########################

Okay successfully uploaded it, however, it is in my next post, on page 2 of this forum thread.

Thanks.<br /><br />Post edited by: Steve Rednond, at: 2009/10/15 05:47