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Re: triaxial test with membrane

 

Hi,

It is just to give some details about strain localization. I don't think you need a menbrane to obtain shear band, it has already been found in a rigid cubical box with the DEM, and experimentally on sand with the apparatus TRITRI in lab. 3S-R. Experimentally they found that the shear band was reflected on the rigid boundaries.

About periodic boundaries, I think I have already seen shear band with periodic boundaries, but shear band are somehow constraint since they have to verify the periodicity.

Best,

Luc

Janek Kozicki a écrit :
Hi,

I'm thinking about implementing membrane in triaxial test, in order
to be able to see localization due to internal shearing.

questions:
1) was it done already by someone, and I missed this?

2) it is maybe not necessary, because periodic boundaries also allow
to see localization due to shearing? (I doubt that, because the shift
on one side is on different height than the shift on right side).

I would do this in following way: detect which spheres are on the
outer boundary (so they are touching the membrane), and push them
inside with some force.

To detect spheres that touch the membrane I will do a Delaunay
triangulation of whole sample, with extra four points added. Each of
those four points is on the exterior of the sample and is a
"membrane point". Any sphere that gets connected through Delaunay
with this point must be lying on the boundary and is in contact with
membrane.

do you have any comments on that?

I suppose that eigen has Delaunay triangulation. Previously I was
using wm3 for that.


--
Luc Sibille

Université de Nantes - Laboratoire GeM UMR CNRS

IUT de Saint Nazaire
58, rue Michel-Ange - BP 420
44606 Saint-Nazaire Cedex, France

Tel: +33 (0)2 40 17 81 78



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