Question #249830 on Yade changed:
https://answers.launchpad.net/yade/+question/249830
Status: Open => Answered
Jérôme Duriez proposed the following answer:
Hi Cyndie,
Let me try to answer your questions:
§ "In order to avoid that, I have applied the same engine twice ..."
-> I'm sorry, I do not get your point. This engine is intended to deform
(hence, to be applied to) a whole box, not a corner.
"I am using kinemCNDEngine with rigid frictionless walls- does it still working
under such conditions or should I have periodic boundaries or add friction to
my rigid walls?" and following § "The same problem..."
-> As soon as you deal with a box defined as in Fig. 1 of [Duriez2011], the
engine "is working". On the other hand, you can not use it in periodic
boundaries (where there is no box..). About friction, I used walls friction for
reasons stated in § 2.2 of [Duriez2011]. The frictionless feature that you're
currently using may explain that one of your "tho" is ~ 0. The non-symmetry may
maybe arise from a non quasistatic situation ? I'm sorry to not be more precise
here, I never measured stress inside the samples when I used this engine, only
normal and tangential stresses acting on upper plate (that by the way appears
reasonnably equal to the ones of lower plate, see Fig 2.17 and 2.18 of
[Duriez2009])
"- Can the upper and bottom plate move vertically?"
-> No. Quoting the doc, this engine "perform(s) a constant normal
displacement shear, by translating *horizontally* the upper plate". The
constant normal displacement (CND) condition means that the vertical distance
between these two plates is constant. So vertical movements of the upper and
bottom plates are not imposed by this engine. They might be allowed by the
three other "Kinem.." engines designed to impose other classical - for
interface media - loading conditions.
"Is the point (2D)/the line (3D) joining the vertical and the upper plate still
the same during the test?"
-> This point
* evolves in global coordinates frame
* correspond to different material points of the rotating vertical plates
during loading
* is the same material point of the upper plate (its extremity)
Note that examples/simple-shear/simpleShear.py illustrates (in a
mechanical meaningless case, because of a nonadequate spheres sample)
how the box is deformed with this engine, and that § 2.2 and 2.3 of
[Duriez2011] (sorry to quote it again..) should be quite explanatory.
Jérôme
[Duriez2011] : https://www.yade-dem.org/doc/publications.html#duriez2011 (tell
me if you can not access to fulltext)
[Duriez2009] : see corresponding entry in
https://www.yade-dem.org/doc/publications.html#master-and-phd-theses
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