LIGGGHTS® - User Forum

LIGGGHTS® related topics can be discussed here: discussion about models, installation, feature requests and general discussion

particles passing through plate in compression simulation

Submitted by pearllin on Sat, 02/10/2024 - 02:00

Hello,

I am a new user of LIGGGHTS. I am trying to perform a compression test with a cylinder being pushed into a bed of particles, and plot the force acting upon the cylinder. However, I have noticed that my particles are simply passing through the mesh, and all the forces being outputted are 0. I am not sure what is going on - I have tried to fix this by decreasing the timestep and moving the mesh slower, but nothing has worked. I've attached my input scripts. Does anybody have an idea as to what may be causing this?

Much thanks,
Pearl

LIGGGHTS: Neighbour list

Submitted by PRASHANT KUMAR JHA on Thu, 02/01/2024 - 12:16

neighbor 0.005 bin
neigh_modify delay 0

fix pts1 all particletemplate/sphere 15485867 atom_type 1 density constant ${solid_density} radius constant 0.004
fix pts2 all particletemplate/sphere 32452843 atom_type 1 density constant ${solid_density} radius constant 0.00236
fix pts3 all particletemplate/sphere 32452867 atom_type 1 density constant ${solid_density} radius constant 0.001

How to set optimal value of bin size so that unnecessary force calculation for the neighbor list can be reduced? How this neighbor size is calculated?

LIGGGHTS-INL, how to observe the von-misses stress within bond

Submitted by WhoIsJH on Tue, 01/02/2024 - 06:40

Hi there

I'm a new in here. Recently, i have tried to simulate the scratch model with sharp tip and flat surface.
I'm using the LIGGGHTS-INL, which is possible to model continuum such as steel or concrete etc with a bonded particle method.

I can build my own model and explain how it work based on the theory.
But, I want to know how observe the stress within the bond. i think i need to modify some code with related to bond part.

Lattice creation

Submitted by krobot on Wed, 12/06/2023 - 12:16

Hello all,
Is it possible to create a lattice with a range of diameter such 2.0:1.0:20.0. And the diameter in the lattice will be randomly distributed. I want to create particle arrangement in a way that a bunch of small particles will covered a big particle. The diameter of the small particle will be different.

Taxonomy upgrade extras:

particle coverage

Submitted by krobot on Sun, 12/03/2023 - 13:19

variable x0 equal 0.0
variable x1 equal 10
variable y0 equal 0.0
variable y1 equal 10
variable z0 equal 0.0
variable z1 equal 10

variable regx0 equal -0.0001+${x0}
variable regx1 equal 0.0001+${x1}
variable regy0 equal -0.0001+${y0}
variable regy1 equal 0.0001+${y1}
variable regz0 equal -0.0001+${z0}
variable regz1 equal 0.0001+${z1}

Installing VTK

Submitted by Tannaz on Mon, 11/27/2023 - 00:55

I attempted to install VTK by following the procedure outlined on this website: [https://vtk.org/Wiki/VTK/Configure_and_Build]. However, I encountered a problem during the configuration step with CMake. I believe the expected outcome should resemble the procedure in the website but, I am facing an issue as shown in the attached figure. Can anybody help me with this problem?

liggghts ERROR on proc 0: Failed to operate on granular bond history during copy i1

Submitted by JirayutS53 on Fri, 11/17/2023 - 15:48

Hi, everyone.

In LIGGGHTS-PFM, I try to run PRM with a bonded particles model. I got the following error, does anyone have any idea on this error? Thank you in advance.

INFO: Particle breakage: broke 6674 particles (mass 7.318937) at step 16804
a total of 6674 particles (mass 7.318937) broken so far.
[0] step 16804: nlocal 926 ilocal 800 999 tags 2227 1000 mol 1 1
ERROR on proc 0: Failed to operate on granular bond history during copy i1 (/home/jirayuts53/LIGGGHTS/LIGGGHTS-PFM/src/fix_particledistribution_discrete.cpp:445)

Warning: sub-domain too small to insert particles (in LIGGGHTS-PFM)

Submitted by atul2018 on Thu, 11/16/2023 - 16:27

Hello everyone

I looked online but couldn't find anything that concerns my query.

I am performing pure DEM simulation, where I have a rectangular box. I generate the bed (using insert/pack command) in a rectangular box till half of it then insert particles above the created gravel bed with insert/stream command. I can see that particles are inserted, but I get a warning that sub-domain size is too small to insert particles. The warning looks like:

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