LIGGGHTS® - User Forum

I am running simulations of a ring shear tester and I use the fix mesh/surface/stress/servo command.

I am not completely sure about the way to calculate the tangential shear stress from the values of forces and torques I obtain from LIGGGHTS. As result, I have a global vector with 9 components for access by various output commands. The first 3 components are equal to the total force on the mesh, the next 3 components store the total torque on the mesh.

Hello
while doing post processing, I wrote the commond : lpp dump*.chute
but it showed the following message
Command 'lpp' not found

Hey guys,

I use the fix bond/create/gran:
fix bondcr11 all bond/create/gran 10 1 1 0.5 1 100 prob 1 123457

The simulation works for a probability=1 but when I reduce the probability I get the segmentation fault.
*** Process received signal ***
Signal: Segmentation fault (11)
Signal code: Address not mapped (1)
Failing at address: 0xb8

I looked for this error but I don't know how to fix it. Does anybody have an idea?

Thanks for considering my request.

Hi all,

I am doing a triaxial test using LIGGGHTS. After I consolidated my sample in a cube to a constant confining pressure 50kPa, I want to set one boundary which can be penetrated by the small particles while keeping the big particles insides. During this process, the small particles will penetrate through the boundary suddenly and the cube sample will suddenly deform (the volumetric strain could be even 7%).

Hello everybody, I'm writing to know if someone has an example of an eccentric funnel flow simulation. My idea is to run a simulation and use the output to create an animation. I could fulfill a cylindrical flat-bottom silo and discharge it through an eccentric outlet, but the result resembles much more a mass flow.

So, I guess the physical properties are not corrected.

Any help are more the appreciated.

Greetings

Hi, all,
I'm trying to analyze powder spreading process of additive manufacturing.
In my case, a cylindrical roller rolls on a bed of deposited powder and spread it to make a new layer on the fusing bed like shown simplified in the attached figure.
My question is how to rotate and translate the roller at the same time.
I have not come up with an idea to move the center of rotation.
Thank you in advance.

Akio

WARNING: time-step is 28.194306 % of rayleigh time (../fix_check_timestep_gran.cpp:200)
WARNING: time-step is 14.155515 % of hertz time (../fix_check_timestep_gran.cpp:208)

I can't help me solving this problem with help of other discussions on forum related to this concern. Can anyone kindly help me with this problem in simpler way..?

I am using lj units to simulate sheared granular flows involving cohesive particles. According to 'LIGGGHTS Documentation', in lj units mass , sigma and epsilon of particle are set to one. In case of chemical bonds, epsilon is depth of the potential well. In case of granular matter what exactly is epsilon ? How do you define this quantity for granular matter ? Can somebody please help me ?? I am stuck here for a long time....

Dear community,
I used LIGGGHTS version 3.7.0 and want to run simple case (free fall by gravity of a single particle) without damping (gamma_n =0 and gamma_t = 0) , but my inputscript below doesn't work (any changes of gamma_n and gamma_t don't affect to movement) .
Can somebody help me with correct writing to change this parameters?

Best , regards Furkhat

#Contact model example

atom_style granular
atom_modify map array
boundary m m m
newton off
communicate single vel yes
units si

Hi everyone,

I have been working on a script for quite a while now and I am unable to print data to a text file.

I am working with two different multi-sphere bodies. I need to know the position, velocity, forces.... on the Centre of Mass and have this data printed in a text file (csv, txt, dat...). For this I am using the next work flow:

1.- Compute command:

#-------Define Compute to Calculate the Properties of Individual Multi-sphere Bodies (clumps)------#