Position of Mesh

Submitted by Venkataraman on Tue, 01/08/2019 - 14:17

Hi,

I need a clarification. I am simulation triaxial tests on soil. I am using Servo walls on the sides and top to give a constant confinement and move my bottom mesh with a velocity.

To print the volume, I calculate the position of the walls.

I use variable NAME equal f_SERVOFIXNAME[9]
This outputs the coordinates of the mesh in Z direction taking initial position as 0.
Also for the moving mesh I use the same command Variable NAME equal f_STRESSWALLNAME[9]
Does the both command output the same value (i.e) the coordinates of the mesh taking initial position as zero or this there any difference ?

Kindly clarify my doubt.

Thanks,
Venkataraman

Forums:

arnom's picture

arnom | Mon, 01/14/2019 - 11:43

Yes they will take the origin as initial position. There is the possibility to specify a reference point if you wish to change that.
KR,
Arno

DCS team member & LIGGGHTS(R) core developer

Venkataraman | Mon, 01/21/2019 - 08:10

Thanks for the clarification. I also have a problem, hope you could clear it out.
I am working on Triaxial Compression test on granular particles. I use servo walls for the compression.
The problem is initially the forces are high and my servo walls are in the input positions but as the forces approaches to the target val the particles push away the walls and my desired volume changes.
How to keep the walls in position with the target val. I don't the walls to be fixed in the position through out the test as I want to observe a Volume increase or decrease after a isotropic compression and under shearing.

Thanks,
Venkataraman

kardous | Tue, 01/12/2021 - 10:24

Hello,

I am a new user of liggghts. I have some problem with how to create an stl file of a drum to be called in my model with liggghts afterwards. Do you know with which software it is more simple to create this kind of files please?

In advance thank you for your help!

kardous

Daniel Queteschiner | Wed, 01/13/2021 - 16:15

Salome ( https://www.salome-platform.org/ ) is another option for meshing
Generally, STL files can be stored in text (ASCII) or binary format, for usage with LIGGGHTS make sure to save them in ASCII format.

kardous | Thu, 01/14/2021 - 11:14

Hello,

Thank you so much for your advices. One more question please: as I undrestand for now the meshing of a geometry cannot be done with liggghts but with other softwares like what you cited. But I have a hard time understanding why we need to mesh a geometry before using it in liggghts? Is it possible to use the geometry without mesh?

Thank you for your help.
kardous