The Forced Response application is an add-on to the Ansys Mechanical user interface that enables you to use cyclic modeling. A cyclic symmetry analysis requires that you model a single sector, called the base sector. A proper base sector represents one part of a pattern that, if repeated n times in cylindrical coordinate space, yields the complete model, as shown:
Forced Response Analysis:
Determines the blade response (motion & stresses) due to excitation from neighboring blade rows
The excitation happens at multiples of the rotation frequency of the rotor
Resonance crossing between excitation (EO line) and mode frequency must be identified and forced response estimation is performed
Forced response yields blade fatigue data that can be used for blade life analysis
Forced Response of Cyclic Symmetric Model
Cyclic Mode Superposition (MSUP) Harmonic
Tuned: All blades are assumed identical, and are modeled on single blade
Workflow
Small Stiffness Mistuning in Cyclic MSUP Analysis
In Cyclic Mode Superposition (MSUP) Harmonic analysis:
Mistuned object takes tuned response and adds the mistuning effects of each blade in cyclic analysis
Small mistuning — variation of in blade stiffness should not be more than 10%
Note: The Forced Response Add-on is only available on the Windows operating system. Its use requires an Ansys Mechanical Premium or Ansys Mechanical Enterprise license. If you do not already have the license, contact your Ansys sales representative to obtain one.