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lammps/doc/compute_dilatation_atom.txt
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compute_dilatation_atom.txt
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"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)
:line
compute dilatation/atom command :h3
[Syntax:]
compute ID group-ID dilatation/atom :pre
ID, group-ID are documented in compute command
dilation/atom = style name of this compute command :ul
[Examples:]
compute 1 all dilatation/atom :pre
[Description:]
Define a computation that calculates the per-atom dilatation for each
atom in a group. This is a quantity relevant for "Peridynamics
models"_pair_peri.html. See "this document"_PDF/PDLammps_overview.pdf
for an overview of LAMMPS commands for Peridynamics modeling.
For small deformation, dilatation of is the measure of the volumetric
strain.
The dilatation "theta" for each peridynamic particle I is calculated
as a sum over its neighbors with unbroken bonds, where the
contribution of the IJ pair is a function of the change in bond length
(versus the initial length in the reference state), the volume
fraction of the particles and an influence function. See the
"PDLAMMPS user
guide"_http://www.sandia.gov/~mlparks/papers/PDLAMMPS.pdf for a formal
definition of dilatation.
This command can only be used with a subset of the Peridynamic "pair
styles"_pair_peri.html: peri/lps, peri/ves and peri/eps.
The dilatation value will be 0.0 for atoms not in the specified
compute group.
[Output info:]
This compute calculates a per-atom vector, which can be accessed by
any command that uses per-atom values from a compute as input. See
Section_howto 15 for an overview of LAMMPS output options.
The per-atom vector values are unitlesss numbers (theta) >= 0.0.
[Restrictions:]
This compute is part of the PERI package. It is only enabled if
LAMMPS was built with that package. See the "Making
LAMMPS"_Section_start.html#start_3 section for more info.
[Related commands:]
"compute damage"_compute_damage.html, "compute
plasticity"_compute_plasticity.html
[Default:] none
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