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Example Probabilistic Design Analysis

See the /PDS, PDRESU, PDSAVE, and PDEXE command descriptions for more details.

Note

In addition to probabilistic design data, the jobname is saved to the probabilistic design database file (Jobname.PDS). Therefore, when a probabilistic design data file is resumed (PDRESU), the jobname saved in that file will overwrite the current jobname (/FILNAME).

You can use the PDRESU command (Main Menu> Prob Design> Prob Database> Resume) in an interactive session to resume probabilistic design data that was created through a batch run, thus allowing convenient interactive viewing of batch probabilistic design results.

1.7.3. Clearing the Probabilistic Design Database

The probabilistic database is completely separate from the database. This usually means that saving and resuming the database has no effect on saving and resuming the PDS database. However, if you issue the /CLEAR command to clear the database, then the PDS database is also cleared. For this reason you should never use the /CLEAR command as part of your PDS analysis file. Clearing the PDS database has no effect on the database.

For clearing the probabilistic database you have two options. You can clear the entire PDS database or just the results and solution portion. The latter maintains the probabilistic model definition (the random input variable definitions, correlations, and random output parameter definitions). Clearing only the solution and results part of the PDS database is helpful if you want to modify the probabilistic model (change RVs, set correlations between RVs or RPs, etc.). After you have performed a probabilistic analysis, the PDS will not allow you to change any of the probabilistic model details. This ensures consistency

of the probabilistic model with the results.

To clear the probabilistic design database:

Command(s): PDCLR

GUI: Main Menu> Prob Design> Prob Database> Clear & Reset

Because the database is not affected by the PDCLR command, it may also be necessary to clear the database if the resumed probabilistic design problem is totally independent of the previous one. See the /CLEAR command for details.

1.8. Example Probabilistic Design Analysis

In the following example, you will perform a probabilistic design analysis of a simple indeterminate three-bar truss. This analysis uses the Direct Monte Carlo method.

1.8.1. Problem Description

You will analyze the effect of variation in the three-bar truss cross-section that is subjected to a force with both vertical and horizontal components.

1.8.2. Problem Specifications

The loading for this example is a force of 20000 lbs. located at the vertex of the three truss members. The force acts at a 45° angle from the vertical direction.

The following material property is used for this analysis:

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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