yade-dev team mailing list archive

[Klaus Thoeni <850864@xxxxxxxxxxxxxxxxxx>]

Hi Anton,

some time ago I had a quick look into that problem as well. Actually I 
mentioned the problem to Dion from ESyS-Particle and he told me that they are 
solving this problem by distinguishing contacts with vertices, edges and 
facets. I think the sequence of checking is important too.

You are familiar with ESys, aren't you? You could ask Dion where exactly the 
code for this problem is.

HTH and thanks for looking at this problem!

Klaus

On Tue, 18 Sep 2012 03:41:08 AM you wrote:
> Dear developers,
> 
> I was trying to fix the bug, but I have got a problem, which I cannot solve
> for the moment. As you know, problem appears, when the sphere touches
> (penetrates) on the edge of 2 or more facets and gets from all of them the
> forces. Which is not quite correct.
> 
> I was trying to implement the following fix. Facets are united in "chains".
> The chain consists of the facets, which are in the common case building a
> "surface". So the sphere can interact at the same time only with 1 facet
> of the chain. All other interactions of the sphere with other elements of
> the same chain are switching off.
> 
> The fix is working relatively good for quasi-static tasks. But when a
> sphere rolls over the surface, it "falls" down after the first facet.
> Because on the edge it should take an additional force from the "next"
> facet, which is not happens. That is what we tried to avoid.
> 
> I hope you understood, what I mean. If not, let me know, I will try to
> explain by other words. It would be interesting to check other DEM-codes,
> how this problem is solved there (if it is solved). Also comments and
> suggestions are welcome.
> 
> Thank you.
> 
> Anton

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You received this bug notification because you are a member of Yade
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https://bugs.launchpad.net/bugs/850864

Title:
  strange facet-sphere behaviour

Status in Yet Another Dynamic Engine:
  Confirmed

Bug description:
  See https://answers.launchpad.net/yade/+question/171223

  Spheres that are exactly on an edge between facets behave strangely.
  Maybe related to other (closed, but never solved) bugs in sphere-
  facet.

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