# /STOP

Engine Keyword The Engine is stopped, due to reached energy error ratio criteria, total mass ratio criteria or nodal mass ratio criteria.

## Format

/STOP

 Emax $\text{Δ}{M}_{\mathrm{max}}$ $\text{Δ}{N}_{\mathrm{max}}$ NTH NANIM NERR_POSIT

## Definition

Field Contents SI Unit Example
Emax Energy error ratio. Defined as the ratio of the current simulation energy to the initial energy plus the work added in the system. Unlike the energy error listed in the Engine output file, this value can be greater than 0.999 (99.9%). By default, the run is stopped, if the absolute value of the energy error is exceeded. To only stop for positive energy error, use NERR_POSIT =1.

Default = 1030

$\text{Δ}{M}_{\mathrm{max}}$ Total mass added ratio criteria is defined as the ratio of total added mass of the model at a given time divided by the initial total mass.

Default = 1030

$\text{Δ}{N}_{\mathrm{max}}$ Nodal mass ratio criteria. Defined for each node as the ratio of its mass divided by its initial mass. The computation is stopped; if, at least, one node meets the criteria.

Default = 1030

NTH
= 0 (Default)
The Engine is stopped without Time History file.
= 1
A Time History file is written if the Engine is stopped, due to energy error ratio criteria.
NANIM
= 0 (Default)
The Engine is stopped without animation file.
= 1
An animation file is written if the Engine is stopped, due to energy error ratio criteria.
NERR_POSIT
= 0 (Default)
The Engine is stopped when the absolute value of the energy error is more than Emax
= 1
Only positive energy error is checked for stopping the Engine. Engine is stopped when the energy error is more than Emax.

1. Energy error ratio:
$\frac{{E}_{k}+{E}_{k}^{r}+{E}_{i}}{{E}_{k,1}+{E}_{{}_{k,1}}^{r}+{E}_{i,1}+{E}_{wk}-{E}_{wk,1}}-1$
Where,
${E}_{k}$
Translational kinetic energy at current time.
${E}_{k}^{r}$
Rotational kinetic energy at current time.
${E}_{i}$
Internal energy.
${E}_{wk}$
Work of external forces (energy brought to the system).
${E}_{,1}$
Energy at beginning of the RUN (not at time t=0).
2. To find the divergence of the Engine run, it is better to only check for the positive energy error and not the negative energy error. To find early divergence, it is recommended to use NERR_POSIT = 1, NTH = 1, NANIM = 1, and a relatively low value for Emax.
3. The total mass criteria is defined as the ratio of total added mass at a given time divided by the initial total mass.
4. The nodal mass ratio criteria is defined for each node as the ratio of its mass divided by its initial mass. The computation is stopped, if at least one node meets the criteria.
5. A restart file is written, if the Engine is stopped, due to one of these events.