LIGGGHTS® - User Forum

Hi everyone,

I am trying to model a cone penetrometer test (CPT) in a volume of sand and I would like to compute cauchy stresses in order to get shear lines but I can't find a way to do that. I don't think that the command compute/stress gives that kind of results.

Is there a way to compute them using Liggghts?

Regards,

Abdellah

Hello all,
fix move all move/mesh mesh cad1 rotate ... rotates the mesh along the axis specified.
for eg: motion similar to rotation of earth around the sun can be done using the above fix.

My question is: Is there any fix to define the motion similar to moon roationg around earth where it is tidally locked.

Perhaps you can understand better if you see the picture attached. I would like to get motion similar to the bottom half of the pictue.

cheers,
manton

I want to specify two friction angles for a simulation - one for between pairs of grains, and a lower one between grains and walls. For preliminary simulations, I have been using the following to define friction:

fix m4 all property/global coefficientFriction peratomtypepair 1 ${intfriction}

it is not diffcult to build liggghts by Visual Studio by nmake command, can office source code give a .sln file ?

Hi everyone,

- is it possible to relate cohesive energy density (CED) to surface energy (gamma), or are they calculated completely differently ?

- I understand that the values of CED is calibrated experimentally. What I am trying to do now is to find an estimation range for CED to some pharmaceutical powder. So, is it possible to find some of these values directly somewhere or do I need to do some experiments before I can use this model for my powder ?

Thanks in advance,

Luton

Hi every one....!
i am trying to simulate a mixer that contain glass beads with impeller in the middle.I am a new user of LIGGGHTS. i want to simulate wet mixing with 4 % moisture content,my problem is that i don't know how to add moisture content in the attached input file.Attached file is actually for dry mixing. My system contain 27000 glass beads with 3 mm dia.

Thanks every one.

Hello everybody,

each simulation run it appears the following warning after the "Setting up run...".

WARNING: Energy calculated for multisphere particles is currently not correct (../fix_multisphere.cpp:1014)

Does everyone knows how to solve the problem ?
A typical multisphere command in my code looks like this :

fix ms1 all particletemplate/multisphere 1 atom_type 1 density constant 1566 nspheres 552 ntry 1000000 spheres file data/mstemplate scale 0.001 type 1

Thank you!

Command ”compute pair/gran/local" calculates a local array, of witch the row number equals the number of pairs. So how to get the exact rows on a specified step?
thankyou

Hi all,
After insertion of particles, I want compact the particles with a controlled stress, so I use the mesh/surface/stress/servo command. I followed the instruction of manual and tutorial, but when I using the following commands:

fix sslab all mesh/surface/stress/servo file meshes/slab3_mesh.stl type 3 stress on com 1.75 0. 0.006 &
ctrlPV force axis 0. 0. 1. target_val -10. vel_max 1. ratio 0.01 mode auto
fix tempslab all wall/gran model hertz tangential history mesh n_meshes 1 meshes sslab

I am wondering whether it is possible (or someone has already implemented) to model electrical current running through packed arrangement of particles?

Effective conductivity should depend on the contact area between particles.
So that effectively particles centers are connected with pieces of wire of various diameter (various resistance depending on contact area).

In my understanding it should be analogous to heat transfer, so technically possible using LIGGGHTS.

Am I right or is it more complex than I think?