Shear in-situ stress

PFC
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How to apply an in-situ stress state that include a shear stress component in PFC 6.0 version:
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Hello Xiongyu,

Applying in-situ stresses in DEM codes is a bit more involved then in continuum codes. However, PFC does have a command called ball tractions, that allows the user to specify a stress tensor or gravitational stress and PFC will modify ball-ball and ball-facet tractions to generate the provided state of stress. More information on this command can be found here - ball tractions command — PFC 6.0 documentation
Note this command applies to balls and rblocks, but not clumps. An example that uses this logic for rblocks is provided here - Data Files for “TunnelBBM” Example — PFC 6.0 documentation
Also, to check that the specified stress does indeed develop you can create measurement circles in your model to check the state of stress. More information on use and implementation of measurement circles are given here - Measure — PFC 6.0 documentation

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Hi Dblamksma
I want to use the command of ball tractions to define the stress boundaries.
"ball tractions ratio 1.271 0.815 direction-x 0.94 0.342 0 "
However, an error was thrown out as ‘Unused extra parameter 7 (0.94) found on command line.’
Do you know the reason?
Thanks

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Hello @Hansenn, At first glance I am not sure why an error would be thrown for that command. Are you using PFC3D or 2D?

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I am using PFC3D 7.0. And I use the command of ‘ball tractions’ based on the manual. This error also makes me confused. I am wondering whether this is a bug of PFC3D. Or there is something I overlooked. If possible, please test this command. Thanks.

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Hello @Hansenn,

We discovered this is indeed a bug and are currently fixing it. The fix will be available in the next update, however, I don’t anticipate the update being available until next month.

We may be able to find a work-around with FISH if this is something that is urgent.

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Thanks. Dblanksma. I can wait for the updated version.