LIGGGHTS® - User Forum

Hello i'm using a servo wall for a ring shear cell. Now i want to calculate the forces acting on the servo wall during a shear run. I have not been able to output the forces data. Can somebody help me? How can i output the data over time into a single .txt file. Thanks a lot!

Hello all,

We (my tutor and I) would like to study faults with DEM. We are interested in applying time- and temperature dependent contact laws. We understand we need to create our own pair_style. This one will be as the Hertz law. But friction coefficient (and maybe some other parameters) depends on time and temperature.

1. How is it possible to put the temperature of a particle into the new contact law ?

Is it possible to have different atom types for individual spheres in a multisphere?

Hello,

till now i have been using a pre compiled windows version of liggghts(not made by me) and wanted to do the switch over to ubuntu to hopefully speed up my simulations, since that version just uses 25% of my Cpu.
Now when i use the make auto command i get the following message:

Makefile:456: *** 'Could not compile a simple MPI example. Test was done with MPI_INC="" and MPICXX="mpicxx"'

I tried setting the MPICXX_USR to my mpi folder and tried setting CXX_USR=icpc, nothing changed.

Dear Ladies and Gentlemen,

is it possible to assign in Liggghts time dependent temperature profiles to the particles?

My plan ist to calculate the thermal expansion of my particles in dependence ofhe thermal expansion coefficent and the timedependent temperature.
So far I assign the temperature in that way:

fix 1 all heat/g
ran initial_temperature 373.15 contact_area overlap

Is it possible to print the temeprature of each particle in a text file?
Maybe in that way?

Hello Team,

can we have fix deform applied to an orthogonal box?

That is, when we use fix deform (say shearing in the x-direction) on a triclinic box, the box deforms and a linear velocity profile is developed.

Can we get the same linear velocity profile without deforming the box?

All 6 faces are periodic.

Thank you.

Hi, for school I am working on a liggghts project. I have drawn my geometry and want to use it in my liggghts simulation. I have already done this before without any problems, however, now whatever I try I get the following error message:

ERROR on proc 1: Fix mesh: Bad mesh, cannot continue. You can try setting 'curvature' to 1e-5 or lower or use 'curvature_tolerant yes' (../surface_mesh_I.h:648)

Hello
I am running a fiber network simulation using LIGGGHTS-flexible fibers version.
I want to calculate the average stress in x direction for a specified region "stress_region". I am trying following commands to execute the same.

compute sigma stress_region stress/atom bond
compute sigma_x reduce ave c_sigma[1]
variable stress_x equal c_sigma_x[1]

I believe variable stress_x should give me the average stress in X direction for a region "stress_region "

However I am getting the following error: "Invalid compute style"

Hello,

I am a beginner of LIGGGHTS. I am troubled by the meaning and effect of the keyword com in servo command
eg:
fix x0 all mesh/surface/stress/servo file meshes/x_0.stl type 1 scale 1 com 0.5 0.5 0.5 ctrlPV force axis 1.0 0.0 0.0 target_val 5e4 vel_max 1

In the document, the com was described as the center of mass. I do not understand what it does. I try to change its value, but it seems to get
the same result.

Can anyone help me?

Thank you!

Wang Xiukai

Hey everyone,
I am a third year undergrad in Aerospace engineering.