Question about cylindrical triaxial test

Hi Henry,

do you need the flexible membrane (woo.pre.cylTriax.CylTriaxTest) or rigid boundary (woo.pre.triax.TriaxTest)? Both could be adapted.

Cheers, Václav

Dear Pro. Václav,
   I want to us the flexible membrane in triaxial test. And the sample mode is generated by other code ( PFC3D). I want to import particle into Woo through the center coordinates of each particles. Can I?
   While in the examples, the sample is generated in the function (woo.pre.cylTriax.CylTriaxTest) . How can I import the generated sample into this function?
Thanks!
Best regard,
Henry

Hi Henry, I added the spheresFrom parameters which you can use. The cylinder will be created inside the packing box, and the spheres must be clipped to the cylindrical shape already (I hope that is OK, removing those sticking out would also be doable). See http://woodem.eu/doc/woo.pre.html#woo.pre.cylTriax.CylTriaxTest.spheresFrom . The file syntax is simple (x y z r), there is some information about it in http://woodem.eu/doc/tutorial/export.html?highlight=spherepack#packings .

I am not sure how far you get with the CylTriaxTest preprocessor for your parameters. It works for the default parameters, but as said in the docs, there is quite a few hardcoded params influencing membrane stabilization etc, which may not be appropriate for your setup. Try and see.

(One of the reasons is that there is no viscosity in the membrane, and the numerical damping is not very suited for membranes, it seems; if you know a good reference about simple extension of the triangular place+shell element to account for viscous dissipation, I will be grateful.)

Cheers, Václav

PS those changes landed in rev. 3634.

Dear Pro. Václav,
    Many thanks for your reply, which is very useful for me to study the WOODEM code. Furthermore, how can I import the clumps of particles? Or may the sample generation can be moved out of the cylindrical triaxial test function (woo.pre.cylTriax.CylTriaxTest)? Which may be more flexible for the use of the function.
    Furthermore, I just to use this function. Maybe there are some question in the studying process.
    Thanks a lot!
Best regard,
Henry

Furthermore, may I use the coupling of FEM and DEM of the Woo to realize the cylindrical triaxial test with flexible membrane boundary?
That is, the flexible membrane is represented by thin solid meshes (FEM ). And the confining pressure is loaded on the FEM model, which then translated to the DEM sample?
Thanks a lot!
Best regard,
Henry

Hi Henry,

I updated the doc at http://woodem.eu/doc/tutorial/export.html#spherepack to mention how to specify clumps (you add a 5th column with clump number).

To move the sample generation out of the routine, it is not easy to see how to integrate that with the preprocessor; loading from an external file seems to be a good compromise. If you need something very complex, let me know and we will look at that specifically. You might also want to prepare the sample with Woo (while I respect PFC as code, I am always astounded how little functionality they manage to sell for how much money ;) not even speaking of Fish ..).

For the memberane simulation, yes, it will do what you need, flexible, and acts on the particles afterwards. Maybe you want to read http://woodem.eu/doc/cases/cyl-triax/index.html for the background of the preprocessor (it was a commercial contract on simulating triaxial test with membrane). HJydrostatic pressure is introduced via surfLoad (http://woodem.eu/doc/woo.fem.html#woo.fem.Membrane.surfLoad) which is adjusted during simulation (0 in compaction phase etc).

Cheers, Václav