[CIG-SHORT] multiple loads in step 18 & step 19

[Charles Williams]

Hi Jeane,

I’m a little unclear on your question.  Am I correct that what you want to do is have a variable surface load with different time histories throughout the nodeset?  Or do you just want a variable surface load that only varies spatially?  If that’s the case, you just need a single nodeset, and you don’t need to provide a load at every location.  You just need enough points to allow linear interpolation (2D variation).  The key is to make sure you provide values that either coincide with or go outside the domain of the surface.

If you want a subdomain, I think the easiest thing is to create a group, because you can perform logical operations on them.  You can then do things like:

group “test_group” remove node with x_coord > 10001

Once you’ve defined the group the way you want you can then create a nodeset from it.

Sorry if I haven’t really answered your question, but I think I need some more details on what you’re trying to do.

Cheers,
Charles



> On 24/11/2014, at 7:05 am, Sauber-Rosenber, Jeanne M. (GSFC-6980) <jeanne.m.sauber-rosenberg at nasa.gov> wrote:
> 
> A number of us spoke briefly with Brad at the Stanford workshop about expanding (3D/hex)
> step18 & step 19 (one surface load at 0,0) to input multiple loads.   IF I would like 
> to input a variable surface load over a portion of the positive Z face, I believe Brad
> suggested creating a separate subdomain/nodeset on the +z face (?)   In CUBIT,  do I create 
> first the +z node set (CUBIT commands in step 1 below) and then I create a subset by removing nodes 
> outside a center region (incomplete CUBIT command in step 2 below)?
> 
> If I should create a subset of the z+ surface to input surface loads  commands:
> 1.	Do I need to input a load at every point in the subdomain to be 
> able to use linear interpolation?
> 2.	Do you put the 0 tractions on the edges of this subdomain or on the 
> edges of +z-face, i.e. such as in  the step 19 example given in the spatialdb/tractions_axial_pressure.spatialdb file?
> 
> I tried but never succeeded in creating a subdomain in CUBIT.
> 
> Step 1:
> # ----------------------------------------------------------------------
> # Create node set for +z face
> # ----------------------------------------------------------------------	   
> group "face_zpos" add node in surface 1
> nodeset 16 group face_zpos
> nodeset 16 name "face_zpos"
> 
> Step 2:
> #-----------------------------------------------------------------------
> #create nodeset for load/unload set
> #-----------------------------------------------------------------------
> what OTHER commands?
> nodeset 17 in surface all with x_coord > 10001 remove
> nodeset 17 in surface all with x_coord < -10001 remove
> nodeset 17 in surface all with  y_coord > 10001  remove
> nodeset 17 in surface all with  y_coord < -10001 remove
> 
> Thanks,
> Jeanne Sauber
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Charles A. Williams
Scientist
GNS Science
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C.Williams at gns.cri.nz