# RSPINT

Bulk Data Entry Defines the rotor spin rates and rotor damping parameters with respect to time during a Transient Rotor Dynamics Analysis.

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
RSPINT ROTORID GRIDA GRIDB SPDUNIT SPTID
GR ALPHAR1 ALPHAR2 WR3R WR4R WRHR HYBRID

## Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
RSPINT 140 2500 2501 FREQ 300
0.04

## Definitions

Field Contents SI Unit Example
ROTORID
setid
Rotor identification number.

No default <Integer > 0>

GRIDA Identifies a grid on the Rotor Line Model.

GRIDA and GRIDB define the positive rotor spin direction. The vector connecting GRIDA and GRIDB is the positive direction vector. The rotor axis is defined using the ROTORG Bulk Data Entry and the two grids (GRIDA, GRIDB) are also specified on the ROTORG Bulk Data Entry.

No default <Integer > 0>

GRIDB Identifies a grid on the Rotor Line Model.

GRIDA and GRIDB define the positive rotor spin direction. The vector connecting GRIDA and GRIDB is the positive direction vector. The rotor axis is defined using the ROTORG Bulk Data Entry and the two grids (GRIDA and GRIDB) are also specified on the ROTORG Bulk Data Entry.

No default <Integer > 0>

SPDUNIT
RPM
Specifies that the relative spin rates are input in Revolutions Per Minute.
FREQ
Specifies that the relative spin rates are input in revolutions (cycles) per unit time.

No default

SPTID
<Integer > 0>
References a TABLED1 entry which specifies the rotor speeds with respect to time. 3

No default

GR Rotor structural damping factor. 4 5

Default = 0.0 <Real>

ALPHAR1 Scale factor applied to the rotor mass matrix for Rayleigh damping. 5 6

Default = 0.0 <Real>

ALPHAR2 Scale factor applied to the rotor stiffness matrix for Rayleigh damping. 5 6

Default = 0.0 <Real>

WR3R Average excitation frequency for calculation of rotor damping and circulation terms for rotor structural damping specified through GR field.

Default = 0.0 <Real>

WR4R Average excitation frequency for calculation of rotor damping and circulation terms for rotor structural damping specified through GE (material, bushing etc.) entries.

Default = 0.0 <Real>

WRHR Average excitation frequency for calculation of rotor damping and circulation terms for rotor structural hybrid damping specified through HYBRID entry.

Default = 0.0 <Real>

HYBRID Hybrid damping. References the identification number of a HYBDAMP entry for hybrid damping specification. 6

Default = 0 <Integer ≥ 0>

1. A RSPINT entry must exist for each rotor line model defined using the ROTORG Bulk Data Entry.
2. GRIDA and GRIDB define the positive rotor spin direction. The vector connecting GRIDA and GRIDB is the positive direction vector. The rotor axis is defined using the ROTORG Bulk Data Entry and the two grids (GRIDA, GRIDB) are also specified on the ROTORG Bulk Data Entry.
3. The TABLED1 entry can be used to specify the various rotor speeds with respect to time. The time values are specified on the X-Axis and the corresponding rotor speeds are defined on the Y-Axis.
4. Rotor structural damping factor ( $GR$ ) can be incorporated as either equivalent viscous damping or structural damping depending on the solution sequence.
(1)
${\left({C}_{R}\right)}_{Structural}=\left(\frac{GR}{WR3}\right){K}_{R}$
Or,(2)
${\left({C}_{R}\right)}_{Viscous}=\left(1+iGR\right){K}_{R}$

Where, WR3 is a parameter defined as a field on RSPINT entry, or by PARAM, WR3. In case both are defined, then WR3 on RSPINT takes precedence. GR is defined as a field on the RSPINT Bulk Data Entry.

The selection depends on the following factors:
• Modal frequency response or Complex eigenvalue analysis
• Synchronous or Asynchronous solutions
• Value of PARAM, GYROAVG
5. The Rayleigh damping value for the rotor is calculated from ALPHA1 and ALPHA2. ${\alpha }_{R1}$ and ${\alpha }_{R2}$ are used to define the Rayleigh viscous damping as:(3)
${\left({C}_{R}\right)}_{Rayleigh}={\alpha }_{R1}{M}_{R}+{\alpha }_{R2}{K}_{R}$
and(4)
${\left({C}_{R}^{C}\right)}_{Rayleigh}={\alpha }_{R1}{M}_{R}^{C}+{\alpha }_{R2}{K}_{R}^{C}$
6. For detailed information on how each type of rotor damping enters into the system equations through their corresponding damping and circulation terms. Refer to Rotor Dynamics in the User Guide.
7. Rotor damping is cumulative and caution should be exercised when multiple damping effects are assigned.