# Parameters: Static Solver

Command ElementModifies a static simulation parameter element.

## Format

```
<Param_Static
{
[ method = "MKEAM"
[ max_ke_tol = "
```*real"* ]
[ max_dq_tol = "*real"* ]
[ max_num_iter = "*integer"* ]
| [ method = { "FIM_S" | "FIM_D" }
[ max_imbalance = *"real"* ]
[ max_error = *"real"* ]
[ stability = *"real"* ]
[ max_num_iter = "*integer"* ]
[ compliance_delta = "real" ]
}
/>

## Attributes

`method`- Specifies the choice of the algorithm to be used for Static or Quasi-static
simulation. For static equilibrium, there are two choices:
- "MKEAM"
- "FIM_S"

For the Maximum Kinetic Energy Attrition Method ("MKEAM"), the relevant parameters are:

`max_ke_tol`- Applicable only if "MKEAM" was chosen. Specifies the
maximum allowable residual kinetic energy of the system at the static
equilibrium point. This should be a small number. The default value for
`max_ke_tol`is 10E-5 energy units. `max_dq_tol`- Applicable only if "MKEAM" was chosen.
`max_num_iter`- Applicable only if "MKEAM" was chosen. Specifies the
maximum number of iterations that are allowed before simulation stops. If
`max_ke_tol`and`max_dq_tol`are not satisfied at this point, the equilibrium iterations should be considered to have failed. The default value for`max_num_iter`is 50.

For the Force Imbalance method, the relevant parameters are:

`max_error`- Applicable only if one of "FIM_S" or
"FIM_D" was chosen. This specifies the upper limit for
the change in the residual of the system equations at the static equilibrium
point. The iterations are deemed to have converged when the maximum residual
in the equations of motion is smaller than this value. The default value for
`max_error`is 10E-4. `max_imbalance`- Applicable only if one of "FIM_S" or
"FIM_D" was chosen. Specifies the maximum force
imbalance in the equations of motion that is allowed at the solution point.
This should be a small number. The default value for
`max_imbalance`is 10E-4 force units. `max_num_iter`- Maximum number of iterations that are allowed before the simulation terminates.
`stability`-
Specifies the fraction of the mass matrix that is to be added to the Jacobian (see discussion on Newton-Raphson method in the Comments section) to ensure that it is not singular. The Jacobian matrix can become singular when the system has a neutral equilibrium solution and the initial guess is close to it. To avoid this, a fraction of the mass matrix (known to be non-singular) is added to the Jacobian to make it non-singular. The value of

`stability`does not affect the accuracy of the solution, but it may slow the rate of convergence of the Newton-Raphson iterations.`stability`should be a small number. The default value for`stability`is 1-10.Note: The square root of the value specified by`stability`is multiplied to the mass matrix and then added to the Jacobian to make it non-singular. `compliance_delta`- Delta used during compliance matrix calculation (default = 0.001).

## Example

```
<Param_Static
method = "MKEAM"
max_ke_tol = "1.000E-05"
max_dq_tol = "0.001"
max_num_iter = "50"
/>
<Param_Static
method = "FIM_S"
max_residual = "1.000E-04"
max_fi_tol = "1.000E-04"
max_num_iter = "50"
/>
```

## Comments

- For quasi-static simulation, only the force imbalance methods are supported.
- For the Force Imbalance method, only a subset of the modeling
elements are supported. The following are not supported:
- Body_Flexible
- Body_Point
- CVCV
- PTSF
- CVSF
- SFSF
- Constraint_Gear
- Constraint_UserConstr
- Force_Contact
- Force_Field

- For a description of the two methods here, refer to the Parameters: Static Solver model element topic.