# compute smd/tlsph/stress command

## Syntax

    compute ID group-ID smd/tlsph/stress

-   ID, group-ID are documented in [compute](compute) command
-   smd/tlsph/stress = style name of this compute command

## Examples

``` LAMMPS
compute 1 all smd/tlsph/stress
```

## Description

Define a computation that outputs the Cauchy stress tensor for particles
interacting via the Total-Lagrangian SPH pair style.

See [this PDF guide](PDF/MACHDYN_LAMMPS_userguide.pdf)\_ to using Smooth
Mach Dynamics in LAMMPS.

## Output info

This compute calculates a per-particle vector of vectors (tensors),
which can be accessed by any command that uses per-particle values from
a compute as input. See the [Howto output](Howto_output) doc page for an
overview of LAMMPS output options.

The values will be given in [units](units) of pressure.

The per-particle vector has 7 entries. The first six entries correspond
to the xx, yy, zz, xy, xz and yz components of the symmetric Cauchy
stress tensor. The seventh entry is the second invariant of the stress
tensor, i.e., the von Mises equivalent stress.

## Restrictions

This compute is part of the MACHDYN package. It is only enabled if
LAMMPS was built with that package. See the [Build
package](Build_package) page for more info.

This quantity will be computed only for particles which interact with
the Total-Lagrangian SPH pair style.

## Related commands

[compute smd/tlsph/strain](compute_smd_tlsph_strain), [cmopute
smd/tlsph/strain/rate](compute_smd_tlsph_strain_rate)

## Default

none