LIGGGHTS® - User Forum

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.

Hello Liggghts Users,

i want to move my mesh between two points at a given frequency along the x-axis. I´m using the linear/variable command for this since i also have to add rotation around the x- and y- Axis later down the line at the same frequency. I used the wiggle command before instead of linear/variable but that has led to an unwanted overshoot.

My Problem now is the correct use of the linear/variable command.

The Error is:
ERROR: Invalid syntax in variable formula

I use the following command line:

Hello!! I am very new to LIGGGHTS. I am trying to model the particle settling on a solid bed for the simulation of Laser Powder Bed Fusion(LPBF). Is anyone working on the same topic or has done the same in the past? It would be really helpful as I am running out of time.

Hello LIGGGHTS forum,
really appreciate your help.

I want to save the distance between particle insertion surface and mesh surface in dump file.

How can I save this distance/height ?

Thank you.

Hi everyone,
I am trying to simulate the angle of repose test by lifting cylinder test, according to the paper by Thomas Roessler, "Scalability of angle of repose tests for the calibration of DEM parameter"
I have two questions:
1) When I tried to move my cylinder up to let the particles flow out, my particles do not flow out. The particles seem to be stuck with the cylinder . Does anyone know how to fix this?

Hi Everyone

I am trying to import particle configuration by using [read_data] command. But I am getting the following error.