LIGGGHTS® - User Forum

I am trying to set up a basic homogeneous cooling simulation. I am loading in 1000 particles in a periodic domain. Initially, I run the simulation with coefficient of restitution equal to 1. To me, this should result in a nearly constant kinetic energy for the system. However, the velocities shoot way up (depending on time step size). Eventually the kinetic energy decreases as expected after a lower coefficient of restitution is set. My question is what is causing the kinetic energy to increase? This should not even be physically possible if there is no gravitational force.

Hi, I am trying to run a triaxial test. I have defined properties as:
# interaction property [NOTE: Young's modulus value is same for both particle and wall]
variable y1 equal 65e9 # Young's Modulus particle-particle [Pa]
variable y2 equal 6.5e9 # Young's Modulus particle-wall [Pa]
variable us_pp equal 0.15 # Coefficient of static friction particle-particle
variable us_pw equal 0.05 # Coefficient of static friction particle-wall
variable ur_pp equal 0.01 # Coefficient of rolling friction particle-particle

Hello

I want to fill a defined region with fibers. I am creating fibers calling a text file which consists particles' coordinates and radius. I am calling it using the commands below:
fix pts1 all particletemplate/multisphere 15485863 atom_type 1 density constant 2500 nspheres 10 ntry 1000000 spheres file mult.txt scale 0.01 type 1
fix pdd1 all particledistribution/discrete 15485867 1 pts1 1.0
Here 'mult.txt' has the coordinate information

Dear Forum,

I was wondering if it is possible to make DEM simulations while some particles are steadily expanding at a given rate. Should it be enough to mark the particle radius as a variable and make it evolve with time?

Regards,

Oier.

Hello Everyone,

I have a query regarding the simulation I am doing right now regarding slurry flow (carbon particles moving in a flowing water) in a microchannel to simulate charge transfer between particle-collector and particle-particle.

Hi
How can we insert single geometry multiple times, also how can we control their orientation.
You will get more idea about the problem in following video links:
https://www.youtube.com/watch?v=FmAm6QoXeB8
https://www.youtube.com/watch?v=9A5n6p4OmaE

Dear LIGGGHTS experts
I have just started using Liggghts and have two questions regarding the bod models:

(1) Like elastic bonds, can we also model plastic or elastoplastic bonds between the atoms. A typical bi-linear elastoplastic stress strain curve is attached.

(2) Can we model cohesive-zone based bond failure, an example traction-separation curve is attached.

Thanks

Hi
I am a novice to LIGGGHTS.
I am wondering ho I can apply beam boundary conditions on selective particles, such as shown in the video in the following link
https://youtu.be/I01tRnfdZ30

Thanks
Shubham

Hi everyone,
I am doing triaxial test simulation. I want to compute the Unbalance force index (Formula is attached with this post), and change the strain rate accordingly within the script. I have tried to compute contact force and total force on particle and the reduce them to scaler value. But it seem there is a problem.

Hello,

I have a really quick question. I have a spherical region, and I want its radius to change with time. On this
link , you can find the following statement:

"The radius value for style sphere and cylinder can be specified as an equal-style variable. If the value is a variable, it should be specified as v_name, where name is the variable name. In this case, the variable will be evaluated each timestep, and its value used to determine the radius of the region."