LIGGGHTS® - User Forum

Hi Everyone,

I'm pretty new to liggghts and having trouble on understanding and finding out some of the terms such as what is KinEng and rke in the terminal or liggghts log? (where can i find this info?)

I'm currently building DEM granular model with lattice model. and turns out that for some reason the KinEng & rke return as -Nan. during the run.

It is suspected that due to overlapping integration between lattice section and "fix integr all nve/sphere" (line64).

Please help

thank you in advance

code:

Hi all !

I am a new LIGGGHTS user and followed EngineerDo's tutorial for the silo particle dimension (https://www.youtube.com/watch?v=bCfCpjNuSVQ).

I used his code and tried to modify it for my problem, i.e. the generation of a powder bed particle for Selective Laser Melting. I created my substrate, which consists of a rectangular box of 0.5x0.3x0.3 (L,w,h, all in mm), and a blade which should spread the particles on the substrate after they fall from the insertion face.

Hi All, I an using insert/stream to insert particles from a plane. I have tried inserting particles of different sizes in turn by using two insert/stream, namely inserting one size first, unfixing ins, and then the other ins, it didn't work. Can anyone give any advice?

Does anyone know how per multisphere quantities can be manipulated like per atom quantities? For example, with a mixture of spheres, I could do the following computation if I would like to:

variable velx atom vx
variable vely atom vy
variable sqvel atom sqrt(v_velx^2+v_vely^2)
compute vel all reduce ave v_sqvel

Hi,
I am new to LIGGGHTS and have been having trouble finding information on how quaternions are calculated.

This is the second time to ask this question since nobody answered the first and I really need an answer for this issue!

I'm trying to make a triaxial compression test in two scripts. First, generating particles using insert/stream in a cubic region then unfix all walls and save a restart file. Second, fix new servo walls and apply equal pressure from all walls except the base wall and after reaching the target confining pressure, I only increase the pressure of the upper wall to apply vertical compression on the sample. I use kp = 1, ki = 0, kd = 1e-6.

I'm modelling a sample with superquadric particles. Particles are inserted using insert/stream into a cubic cell. When I measured the porosity (void fraction) of the whole sample after insertion, it's found to be 0.35 (sample is very dense). How could I increase this value in order to get looser packed samlpe.

Thanks for your time.

Hi all,

i have a question regarding the friction models that can be used in Liggghts.
coefficientFriction - this is the static or internal friction
coefficientRollingFriction - rolling friction as in the name

Where can we define a sliding friction coefficient? Is there an implemenation of sliding friction in Liggghts? I have found 1 post where coefficientFriction is regarded as the sliding friction Coefficient, which should be wrong?!

Hi
Can anyone guide me on how to install LPP for LIGGGHTS 3.8.0 in Ubuntu 20.04.LTS. as I am finding error message as python 3 is installed instead of Python.

Thanks in advance.

Hi, I have a question about the value of the force and how it come from.

I did the simulation and dumped the file for contact and atom.

I get the atom data using 'dump aa all custom time id type x y z vx vy vz fx fy fz ...'

And the contact data using 'compute bb all pair/gran/local id pos force_normal' and dump it.