OS-E: 6010 Rotor Unbalance using Modal Frequency Response Analysis

This example is used to find the unbalance frequency in the Rotor using modal frequency response analysis in OptiStruct.



Figure 1. FE Model

Model Files

Refer to Access the Model Files to download the required model file(s).

The model files used in this example include:
  • RD_MRF.fem
  • RD_MFR_Unbal.fem

Model Description

This example consists of two coaxial rotors modeled using 1D elements, one end of each rotor is constrained, the same end is attached to stator using rigid elements, and on the other end is attached to the stator through Spring and Damper elements. Dynamic loading condition are applied to the rotors with phase difference and a relative spin between the two rotors are also defined. Multiple methods are used to compare the unbalance in the rotors using modal frequency response analysis.
FE Model 1D Elements
Rotor
CBAR, CONM2
Stator
SPC, CDAMP, CELAS
Junction
RBE2 Elements
Material Material MAT1 Rotor:
Young’s modulus
2×107
Poisson ratio
0.3
Initial density
1×10-3
Reference Guide Entries Keywords RGYRO, ROTORG, RSPINR, DDVAL, DLOAD, DAREA, UNBALNC, DPHASE, RLOAD2, FREQ1, EIGRL

Results

Subcase
1st Peak Frequency
DLOAD
422.60 Hz
Unbalance Force
422.60 Hz


Figure 2. Displacement versus Frequency Plot at the Grid #5