Mechanical APDL Structural Analysis Guide

MXPAND, ...! Number of modes to expand, ...

D, ...! Constraints

SOLVE! Initiates solution

SAVE

FINISH

!

! Obtain the Spectrum Solution

/SOLU! Reenter SOLUTION

ANTYPE, SPECTR! Spectrum analysis

SPOPT, DDAM, ...! Dynamic design analysis method

ADDAM, ...! Acceleration spectrum computation constants

VDDAM, ...! Velocity spectrum computation constants

DMPRAT, ...! Specify damping ratio required if CSM method is used

SED, ...! Specify excitation direction of shock spectrum

NRLS,,, CSM,! NRLSUM mode combinations with Closely Spaced Modes Method (CSM)

SOLVE! Initiates solution

FINISH

!

! Review the Results

/POST1! Enter the database results postprocessor

/INPUT,,MCOM! Read mode combination file

...! Postprocess as desired

...! (PRNSOL; PRRSOL; PRDI; PRNSOL; etc.)

FINISH

See the Command Reference for a discussion of the ANTYPE,MODOPT,D,MXPAND,SPOPT,ADDAM,
VDDAM,DMPRAT,SED, and NRLSUM commands.

6.8. Performing a Multi-Point Response Spectrum (MPRS) Analysis

The procedure for a MPRS analysis consists of six steps:

1. Build the model.


2. Obtain the modal solution.


3. Obtain the spectrum solution.


4. Combine the modes.


5. Review the results.

The first two steps for an MPRS analysis are the same as the steps described for a modal analysis. The
procedure for the remaining three steps is explained below.

Note

MPRS analysis is not available in ANSYS Professional.

6.8.1. Step 4: Obtain the Spectrum Solution

In this step, the program uses mode shapes extracted by the modal solution to calculate the MPRS
solution. The following requirements apply:

• The mode shape file (Jobname.MODE) must be available.

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

Performing a Multi-Point Response Spectrum (MPRS) Analysis