RSPINT

Format

Example

Definitions

Comments

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.