How to set up the radial velocity and the traction BC

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1

Dear LAMMPS users and developers

I am using PERI package, PDLAMMPS. I have two questions.

1. I am trying the analysis similar to fragmentation of metal ring by
Dr. Parks.
   I think it have to use a "variable" command, but not work because
of my incorrect setting.
   Please tell me how to setting the radial velocity for each particle?
   I am wondering if I should use a "read_data" command.

2. In general, it has been used body force density instead of the
traction boundary condition in peridynamics theory.
    But I found the paper by Ha and Bobaru which was described about
traction BC.
    Unfortunately, I haven't read the paper yet, because I don't know
how to get the paper...

    I want to know whether it will add the traction BC in PDLAMMPS for
the future.

Thanks in advance,

Shingo

2

Mike can comment on your Qs further.
But here's a cut at the 1st one. In the fragmentation
example, the particles start with no radial
velocity. That is a result of the impacting projectile.
So no initilalization needed.

Steve

3

To use LAMMPS to do a fragmenting ring example you can apply a radial initial velocity by doing something like the following:

variable initvel variable 100
variable mytheta atom "atan2(y,x)"
variable velx atom "\{initvel\}\*cos\(v\_mytheta\)" variable vely atom "{initvel}*sin(v_mytheta)"
velocity all v_velx v_vely 0.0 sum no units box

I haven't actually tried to run this to be sure the syntax is correct, so you might need to make some minor corrections.

To use a traction-like boundary condition to peridynamic bodies in LAMMPS, you can select a group of particles near the boundary of a peridynamic body, and then use the fix_addforce command to apply a force to that group of particles.

- Mike

4

Thanks Steve and Mike.

To Steve
It was my insufficient explanation. I already knew the example of impact
by a projectile in the PDLAMMPS users guide.
The example of the fragmentation of metal ring I am trying is accelerated
by electromagnetic load.

Therefore, I think it need to setting the initial radial velocity.

To Mike
I seems to have been a big misunderstanding.
I'm going to try it immediately.

2012/6/30 Parks, Michael L <[email protected]...>: