Mechanical APDL Structural Analysis Guide

The mode-superposition transient solution is written to the reduced displacement file,Jobname.RDSP,
regardless of whether the Block Lanczos, PCG Lanczos, Supernode, Subspace, or QR damped method was
used for the modal solution. You will therefore need to expand the solution if you are interested in stress
results.

5.4.4. Expand the Mode-Superposition Solution

The expansion pass starts with the transient solution on jobname.RDSP and calculates the displacement,
stress, and force solution.These calculations are performed only at the time points you specify. Before
you begin the expansion pass, therefore, you should review the results of the transient solution (using
POST26) and identify the critical time points.

Note

An expansion pass is not always required. For example, if your primary interest is the displace-

ment at specific points on the structure, then the displacement solution on jobname.RDSP

could satisfy your requirements. However, if you are interested in the stress or force solution,

then you must perform an expansion pass.

5.4.4.1. Points to Remember

• The .RDSP and .DB files from the transient solution, along with the .MODE,.EMAT,.ESAV and .MLV
  files from the modal solution must be available.


• The database must contain the same model for which the transient solution was calculated.

The procedure for the expansion pass is explained below.

5.4.4.2. Expanding the Solution

1. Reenter SOLUTION.
   Command(s):/SOLU
   GUI: Main Menu> Solution

Note

You must explicitly leave SOLUTION (using the FINISH command) and reenter (/SOLU)

before performing the expansion pass.

2. Activate the expansion pass and its options.

Table 5.3: Expansion Pass Options

Option Command GUI Path

Main Menu> Solution> Analysis Type> Expansion-

Pass

Expansion Pass On/Off EXPASS

Main Menu> Solution> Load Step Opts> Expan-

sionPass> Range of Solu's

No. of Solutions to be Expan- NUMEXP

ded

Main Menu> Solution> Load Step Opts> Expan-

sionPass> Single Expand> By Time/Freq

Single Solution to Expand EXPSOL

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

Transient Dynamic Analysis