Yade

some data lost when saving simulation with O.save()?

Asked by NgocSon-Nguyen

Dear all,

I am a new Yade user. I am using Yade to simulate a triaxial loading test on an assembly of spheres contained in a box . I first compact the sample by moving the walls. At the end of the compaction, I save the simulation with the command O.save('toto.yade.gz'). I verified with the command TriaxialStressController.strain that the strains e11, e22 and e33 are not zero. Then I reload simulation with the command O.load('toto.yade.gz') to perform a triaxial deviatoric compression. Using the same command TriaxialStressController.strain, I see that all the strain values are now zero, while the stress values are saved. For my simulation, I need the strain values at the end of the compaction to calculate the strain with respect the the configuration at the beginning of the test.

Please tell me how I can save the strain values at the end of the compacting phase.

 Thank in advance for your help.

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Jérôme Duriez (jduriez) said : 		#1

Hi,

That's because TriaxialStressController.strain values are computed every time step (modulo computeStressStrainInterval attribute), but not saved during not a save (this strain "attribute" was not defined as to be saved).

Hence, the value can not be get back after a load, and it is 0, which is the "default" value.

If you want to read strain values after a save/load cycle, you have to run few iterations after your load, so that the value is again computed. Maybe one is enough, or computeStressStrainInterval's value maximum. This should not affect so much your measure...

Note, if this is what you want in the end, that you can "reset" strain values at the end of compaction like this:
tsc.height0 = tsc.height
tsc.width0 = tsc.width
tsc.depth0 = tsc.depth

This affects only post-processing computations of strain.

Jerome

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