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Full Version: Howto: Continuum shell stacking direction on cylindrical solid composite section
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Hello,
Here is how I modeled a cylindrical solid section using continuum shell elements in CAE
Material is Elastic-composite-'Engineering Constants'

Stacking direction is critical for a composite material model. In Abaqus CAE the default stacking direction is 3 and there is no way to change it other than hacking the input file.

The stacking direction of a tetrahedral element is determined by (triangular elements have fixed stacking dir -3) the element connectivity. So the key is to use sweep meshing technique to accomplish this.

I assume that you know the basic procedure involved in creating and analyze a model using Abaqus CAE. So:

  1. Go ahead and create a solid-extrusion part
  2. Composite material is engineering constants for 3D properties.
  3. When you create a section, make sure that you select Continuum shell. Else it will not be used while assigning the section to the geometry.
  4. Partition the model if necessary so that we have lines along the radius for sweep direction (see the attached image)
  5. In the mesh module, select sweep and use the 'Redefine Path' dialogue to edit the sweep direction and select the radial line (outward dir) as demonstrated as circled in the attached image.
  6. Then go ahead and mesh the geometry. That's it.


Verify:
Tools>query>mesh stack... See the attached pics (note the colors and the info at the prompt)

Notes:
1. The layup you specify in the section is contained in one single element through the thickness. So if you have multiple element through the thickness (can be adjusted while seeding the geometry) you have that many repeated stacking.
2. To obtain transverse shear stresses, you need to consider several other factors such as number of layers through the thickness or whether you are using parallel processing or not, and so on.

Ref: Use 24.6.1 Shell elements: overview (6.8 documentation)

Hope this helps. Please feel free to provide corrections/comments in this thread. Thanks.

-CJ
thank you. does it work when you specify the stacking direction in the inp file after you meshed the model using the normal metod?
Working with the .inp file directly gives lots of more possibilities than using CAE. For a simple cylinder like that, you can even generate mesh automatically using the keywords *NGEN and *ELGEN.
(12-21-2008 03:19 PM)Van Fanel Wrote: [ -> ]Working with the .inp file directly gives lots of more possibilities than using CAE. For a simple cylinder like that, you can even generate mesh automatically using the keywords *NGEN and *ELGEN.

Would you please write a brief tutorial on this. Might be very useful for beginners like us. thanks
I'm a bit out of time now, sorry.
But if you check ABAQUS' documentation and know a bit about computer programming (not that you need to program something, but you must be trained in logical thinking), everything should be very easy to understand and follow.
Here is something I did a while ago for a cube of elements:
Code:
**
** NODES
**
*NODE, NSET=GLOBAL
1, 0, 0, 0
10, 100, 0, 0
91, 0, 100, 0
100, 100, 100, 0
*NGEN, NSET=BOTTOM
1, 10, 1
*NGEN, NSET=TOP
91,100,1
*NFILL, NSET=GLOBAL
BOTTOM, TOP, 9, 10
**
** ELEMENTS
**
*ELEMENT, TYPE=CPE4, ELSET=ALL_ELEMS
1, 1, 2, 12, 11
*ELGEN, ALL NODES, ELSET=ALL_ELEMS
1, 9, 1, 1, 9, 10, 10, 1, 1, 1
thank you so much man.

JattStoorn

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