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[Paul Pircher <question695058@xxxxxxxxxxxxxxxxxxxxx>]

Question #695058 on Yade changed:
https://answers.launchpad.net/yade/+question/695058

    Status: Answered => Open

Paul Pircher is still having a problem:
Thanks for your detailed answer Bruno!
Nice to hear from one of the authors of the papers that build the foundation on my current research/work.

To make sure I understood it correctly:
The mass of the cylinders can be completely ignored. Only the mass of the nodes is relevant for the simulation and its results (total mass, deflection, deformation, forces etc). Hence, I only need to set the right density for the CohFrictMat for the nodes and I should be good to go in terms of correct body mass (if nodes have a different material than cylinders). To avoid confusion, setting the density of the cylinderConnection material to zero manually won’t do anything. Right?

Or do I need to set the density of both materials (for nodes and
connections) to the same value, so the computation does not get messed
up and I simply ignore cylinder-mass afterwards? I am reffering here to
one of the creator-functions e.g. gmshPFacet().

In other words, what do I need to do in order to set the mass of a body,
that is made out of nodes and cylinders (and maybe PFacets), to a
certain value?

Seems like I am overthinking this and it might be just a simple
comparison between wanted mass and mass of all nodes and setting the
density of all influenced bodies to corresponding value, but I just want
to be sure and safe about that.

For my application I want to simulate a beam with a rectangular cross-
section. So, I will be using many nodes, cylinder/grid connections and
PFacets. Hence it will not be a very short object and I should be “safe”
as small inaccuracies like the spherical caps won’t bother my results.

Furthermore, PFacets seem to never receive a mass, but also the mass of
the nodes does not increase as it did when connections were added.

Thanks again for you answer.

Since I work a lot with deformable structures in yade based on these to papers [1][2] I would have several more questions according that approach. 
Can you recommend or provide resources for that topic? Any further papers, examples or theory? That would help me a lot. 
As an example, what interests me I will write down some questions. Nevertheless, they have nothing to do with mass computation, so this is off-topic. 
-	What’s the difference between grid- and cylinder-connections.
-	Why is it important to set a cohesive material for the nodes with super high cohesive values?
-	How is the bending/mechanical behaviour in a node that connects 2 cylinders computed? (Same thing along a connection that connects 2 PFacets)

Thanks Bruno and I hope I did not flood you with questions. 
Your help is and was very much appreciated!

Best regards,
Paul

[1] https://www.researchgate.net/publication/282996677_A_general_method_for_modelling_deformable_structures_in_DEM
[2] https://doi.org/10.1016/j.geotexmem.2015.07.015

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