Wall stress

JF's picture
Submitted by JF on Fri, 07/09/2010 - 09:51

Hi Christoph,

Concerning the stress computed with the command: mesh/gran/stressanalysis

In my simple compression test, I have these lines:

fix topwall all mesh/gran/stressanalysis topwall.stl 1 1. 0. 0. 0. 0. 0. 0. # Insert top wall
fix bottomwall all mesh/gran/stressanalysis bottomwall.stl 1 1. 0. 0. 0. 0. 0. 0. # Insert bottom wall

fix wall all wall/gran/hertz/history 1 0 mesh/gran 2 topwall bottomwall #Contact properties

fix F_movetop all move/mesh/gran linear 0. 0. -0.0001 units box topwall 1 #Wall motion

dump I_stl all mesh/gran/VTK 1000 post/Stress_file-*.vtk stress # Output files

But I don't have stress computed at the end of my simulation in my files Stress_file-*.vtk.

What am I doing wrong ? Please, can you help me ?

Thanks
Jf

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ckloss's picture

ckloss | Fri, 07/09/2010 - 11:37

Hi JF,

these commands should be correct - did you try to dump more frequently?

Best,
Christoph

tshan | Mon, 11/08/2010 - 14:19

Hi Christoph,

I am interested in this topic and ran this example on my own laptop, but it also seems to have no stress in Paraview.

Could you give me further more details on resolving this issue?

Thank you.

Best regards,
Tong

ckloss's picture

ckloss | Mon, 11/08/2010 - 14:34

Download 1.1.10, it comes with a slightly modified version of JF's example
But still, in the example, you have no long-lasting contact. ie you have to dump more frequently

Christoph

raguelmoon's picture

raguelmoon | Tue, 11/09/2010 - 04:23

Hi Jf,
Please do the same with bottomwall and see the result, if it works then there is problem with your scripting. I can see the result. Otherwise please send your script.
Best,
Ram

Ram

JF's picture

JF | Tue, 11/09/2010 - 11:47

Hi Ram,

As Christoph told us already, if we want to see the stress (Pressure) on the topwall, we need to dump more frequently.
In fact my simulation is too fast and the material parameters are not appropiated. Therefore, the topwall impacts the packing (i.e., At the beginning there is contact time very very short), and the bottomwall does not receive the wave because the time step is too high.

It was just a script to realize your own compression test from a loaded file. I have modified a bit the script (see details below ), you can follow on paraview the pressure from the time=300 (rescale to data range), the topwall still impacts the packing various times.

I hope this will help you

Regards
JF

#
dump D_stl all stl 100 post/Wall-*.stl
dump I_stl all mesh/gran/VTK 100 post/Stress_file-*.vtk stress

#output settings, include total thermal energy
compute 1 all erotate/sphere
thermo_style custom step atoms ke c_1 vol
thermo 100
thermo_modify lost ignore norm no
compute_modify thermo_temp dynamic yes

#insert the first particles so that dump is not empty
run 1
dump dmp all custom 100 post/dump.compression id type type x y z ix iy iz vx vy vz fx fy fz omegax omegay omegaz radius

#run
run 60000 upto

raguelmoon's picture

raguelmoon | Sun, 11/21/2010 - 14:01

Hi Christoph,
JF is right, when we move mesh then it doesn't update stress profile. I dumped with latest version. Please could you provide solution for that?
Thanks,
Ram

Ram