LIGGGHTS® - User Forum

Hi all,

When unfixing a move wiggle fixed for a substrate made of particles, the kinetic energy of these particles wouldn't go to zero unless zeroing velocity by hand, i.e., by using "velocity group zero linear". Any idea?

Selim,

Hi all,

I am trying to understand the 6 components of stress tensor computed by stress/atom.
What are the physical meaning of kinetic energy contribution, angle, dihedral and improper component of the stress tensor?

What should be the keyword listed if I want to compute the stress tensor of a particle packing (sand foundation) under the gravitational force field?

Many thanks

Hi,

I'm trying to understand the values that are calculated with:

dump custom fx fy fz
compute pair/gran/local force
compute stress/atom

therefor I insert 2 particles, but just one particle is integrated. One particle lies on top of the other and gravity loading is on both of them acting.

Dear all,

I have a question about "rotate" command in LIGGGHTS.

The geometry in my work consists of two separate parts. The first one is rotating around a specific axis and the second one is rotating around the first geometry part.
For the first part, there is no problem but how can I simulate rotation of the second geometry part around the first which rotates itself?

Regards,
Shahab

Hello All,

I want to read multiple input data files using read_data command in my simulation. How can i do this?
These data files correspond to different parts of my geometry.

Can someone please help me on this.

Thanks,

Narendra

Hi all,

I am trying to create a single ellipsoid particle to do some comparison with a spherical particle but I have got the following error message:

"ERROR: Fix wall/gran (id zwalls1): requires atom attributes radius, omega, torque (../fix_wall_gran.cpp:88)"

I looked at "fix wall/gran command" & "set command" but I could not find where should I define these a attributes. Could some one please give me some hints about this and how to set the commands associated with ellipsoid style correctly.

Many thanks,

Leader

Hi all,

I am simulating a sand foundation with a linear distribution in mass. When I use "radius uniform mass 0.00015 0.0003", it reminded me "mass distribution not implemented for uniform". What does it mean? How could I solve this problem?

Many thanks,

Su

Hi All,

I have a stl geometry in my simulation. I want to attach (fix) one layer of spherical particles on the surface of this geometry.
How can i achieve it?

Any help will be much appreciated.

Thanks,

Narendra

How to create a assembly of bonded particles in LIGGGHTS?

Please share any example with input script. I have seen that beam fracture in the website but it says under developement. Please shade some light on that.

Thanks in advance

Hi all,

I am simulating a group of particle bonding together ( like a string). I divide a string (or fibre) into a number of balls. By this way, I need to define the bonding peroperties (kn; ks) among these balls so that they can be created and also be broken. I got a nice suggestion from Christian (Richti) in terms of granular bond package. Could anyone share with me more information about this package? how can I get and install it? Does it work on public version of LIGGGHTS? DEM simulation would be strongly limited without bonding.

Thanks,