LIGGGHTS® - User Forum

Hi all,

Is there any command or method to output the cohesion force only?

Kind regards,
Linhan

Hi all,

I want to obtain a vector or array of particle radius.
I use the following commends:

compute rad all property/atom radius
variable ra atom c_rad
variable rb equal ra[1]
if "${rb} >= 0." then "run 1"

But it does not work.

Who can tell me how to use per-atom vectors?

Thank you very much.

Hao XIONG

I am trying to simulate ellipsoidal particles using superquadrics atom_style. Therefore, I started testing with the input file that was released by LIGGGHTS in the example folder (It is attached). For visualization in Paraview, I have compiled it with the Tensorglyph plugins.
I have also attached the video of visualization. I am not able to understand, why after the collision the semi-axes values of both the ellipsoids are changing. For getting a closer look at the problem, I calculated the eigenvalues of both the ellipsoids and found that they are

Hello,

I have a question regarding my build of the 'superquadric' module. I went to the 'LIGGGHTS-PUBLIC/src/MAKE' folder in the 'Makefile.auto' file and modified the USE_SUPERQUADRICS? = "OFF" to "ON". When starting the compilation was warned in the terminal (Ubuntu 16.04 LTS):

Could I simulate the breakage of a distribution of the particles using the LIGGGHTS. Kindly, help me!!

Dear liggghts users,
I want to break multisphere through liggghts. I want to break multispheres when the z coordinate of the multsphere exceeds certain height(here .4 m).
i considered gravity in the +ve z coordinate.
here is my input code.
#Multisphere

atom_style sphere
atom_modify map array sort 0 0
boundary m m m
newton off

communicate single vel yes

#PUBLIC version only supports serial execution
processors * * *

units si

region reg block -0.3 0.3 -0.3 0.3 0.0 0.5 units box
create_box 1 reg

hello everyone,
I wish to simulate one system where particle(sphere or multi-sphere) breaks when it attains some certain height. can anyone please help me with some suggestion? I was going through multisphere/break, but could not figure out threshold value.
any suggestion will be highly appreciated.
thanks in advance.

I know I've discussed this at some level before but, Richti, it sounds as though you've run large simulations with your bonds package with multiple processors? I seem to get intermittent errors when I try to, for example:

Dear all,

I want to use the servo wall (cap) to close a pipe. The granular material in the pipe will built up a pressure on the servowall so that the cap open at an predefined force value. So i need the servo wall to stop at the ending of the pipe.
I specify the servo command as followed:

fix cap all mesh/surface/stress/servo file meshes/cap.stl type 2 com 0. 0. 0. ctrlPV force axis -1. 0. 0. target_val 1 vel_max 0.1 kp 5.

is there a command to stop the wall at a specified coordinate in moving direction of the cap?

Best Regards

Hello,
I am trying to do a triaxial test using LIGGGHTS-WITH-BONDS. I have never really used this software before and I am struggling in understanding what the parameters mean. The particles are in a box were one wall is applying pressure through the mesh/command/stress/servo code. I am trying to calculate the stress the particles are causing on the other walls and my input parameters are as follows:
Minimum ball size -2.5e-4 m
Maximum ball size -4.5e-4 m
Density -2650 kg/m3
Ball and bond elastic modulus - 40 e9 Pa