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Postprocessing a Cyclic Symmetry Analysis

7.4. Postprocessing a Cyclic Symmetry Analysis

This section describes how to perform postprocessing on the solution results obtained from a cyclic symmetry analysis. The following topics are available:

7.4.1.General Considerations

7.4.2.Modal Solution

7.4.3.Static, Buckling, and Full Harmonic Solutions

7.4.4.Mode-Superposition Harmonic Solution

7.4.1. General Considerations

If you exited the program after obtaining the cyclic symmetry solution, use the database (Jobname.DB) that you saved for postprocessing. For more information, see Database Considerations After Obtaining the Solution (p. 192).

The real (basic sector) and imaginary (duplicate sector) parts of the solution reside in the results file. However, the solution does not yet represent the actual displacements, stresses, or reaction forces for any part of the actual structure.

Listing or plotting the sector results causes the program to issue a warning message such as PLNSOL is displaying the unprocessed real and imaginary parts of this cyclic symmetry solution. Furthermore, the basic and duplicate sectors overplot each other if displayed, providing yet another indication that a problem exists.

7.4.1.1. Using the /CYCEXPAND Command

The /CYCEXPAND command is used to expand the cyclic symmetry results to the full 360° model (or a portion thereof ). The command does not modify the geometry, nodal displacements or element stresses stored in the database. Issue the command to expand your basic sector model and obtain the full 360° model displacement, stress, or strain response.

After the expansion, you can plot (PLESOL or PLNSOL) or print (PRNSOL) the results. Other commands (such as NSEL and NSORT) continue to operate on the unprocessed real and imaginary parts of the solution.

Using the cyclic symmetry solution of the basic and duplicate sectors (illustrated in Figure 7.8: Connecting Low and High Edges of Basic and Duplicate Sectors (p. 172)), the /CYCEXPAND command combines the solutions from the two sectors by performing computations on the selected load step (specified via the SET command) to combine the results of the two sectors. The program uses the following response equation for the full structure or assembly:

= A α − B α (7.3)

n

where,

Un = Response of the full structure or assembly (displacement, stress, or strain) for sector number n

UA = Basic sector solution

UB = Duplicate sector solution

n = Sector number for response expansion -- n = 1,2,3,…,N

k = Harmonic index -- (0,1,2,…,N / 2) when N is even, (0,1,2,…,(N-1) / 2) when N is odd. (N is an integer representing the number of sectors in 360°.)

Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information

 

of ANSYS, Inc. and its subsidiaries and affiliates.

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