Mechanical APDL Basic Analysis Guide

create the frequency variable by using either the calculator portion of the variable viewer to define an
equation or the variable viewer's import options.

Note

The displacement time-history values usually result from a transient dynamic analysis.

You can also create the displacement variable using the import options (if the displace-

ment time-history is on a file) or add displacement as a variable.

You must have a time variable defined as the first variable in the variable list (variable

1).

Once you have defined the frequency and displacement time history variables, follow these steps to
calculate a response spectrum using the variable viewer.

1. Specify a variable name in the variable name input area. The name must be unique or you will be
   asked to overwrite the existing variable.


2. Click the RESP button in the calculator portion of the variable viewer. The following dialog box ap-
   pears.


3. Select the reference number of the variable containing the frequency table from the pull down list
   (corresponds to the LFTAB argument for the RESP command).


4. Select the reference number of the variable containing the displacement time-history from the pull
   down list (corresponds to the LDTAB argument for the RESP command).


5. Select the type of response spectrum to be calculated (corresponds to the ITYPE argument for the
   RESP command).


6. Enter the ratio of viscous damping to critical damping as a decimal (corresponds to the RATIO ar-
   gument for the RESP command).


7. Enter the integration time step (corresponds to the DTIME argument for the RESP command).


8. Click OK to save your preferences and close the dialog box. The function
   resp(LFTAB,LDTAB,ITYPE,RATIO,DTIME) is displayed in the expression area of the calculator.


9. Click Enter in the calculator portion of the variable viewer to start the evaluation.

When the evaluation is finished, the response spectrum is stored; the variable name is displayed in the
variable list area for further postprocessing.

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

Additional Time-History Postprocessing