Mechanical APDL Basic Analysis Guide - Ansys

Chapter 8:The Time-History Postprocessor (POST26)
1. Specify a variable in the variable name input area. This must be a unique name, otherwise you will be
prompted to overwrite the existing variable of that name.
2. Define the desired variable expression by clicking on the appropriate keys, or selecting time-history
variables or APDL parameters from the drop down lists.
Result: The appropriate operators, APDL parameters or other variable names appear in the Expression
Input Area.
3. Click the “Enter” button on the calculator portion of the Variable viewer
Notes:
Result: The data is calculated and the resultant variable name appears in the variable list area. The expression
will be available in the variable viewer for the variable name until the variable viewer is closed.
• To find the derivative of a variable “UYBLOCK” with respect to another variable
VBLOCK = deriv ({UYBLOCK} , {TIME})
• To find the amplitude of a complex time-history variable “PRESMID”
AMPL_MID = abs ({PRESMID})
OR,
AMPL_MID = sqrt (real ({PRESMID}) ^2 + imag ({PRESMID}) ^2)
• To find the phase angle of a complex time-history variable “UYFANTIP”
PHAS_TIP = atan ({UYFANTIP}) * 180/pi
Where pi = acos (-1)
• To multiply a complex time-history variable “PRESMID” with a factor (2 + 3i)
SCAL_MID = cmplx (2,3)* {PRESMID}
• To fill a variable with ramped data use the following equation
RAMP_.25BY_0.5 = .25 + (.05 * ({nset} - 1))
• To fill a variable as a function of time use the following equation
FUNC_TIME_1 = 10 * ({TIME} - .25)
• To find the relative acceleration response PSD for a variable named UZ_4, use the following equation
RPSD_4 = RPSD({UZ_4},{UZ_4},3,2)
8.4.2. Batch
In batch mode, you use combinations of commands. Some identify the variable and the format for the output,
while others identify the variable data to be used to create the new variable. The calculator operations
themselves are performed by specific commands.
• To find the derivative of a variable “UYBLOCK “ with respect to another variable “TIME”
196
NSOL,2,100,u,y,UYBLOCK !Variable 2 is UY of node 100
DERIV, 3,2,1,,VYBLOCK !Variable 3 is named VYBLOCK It is the
Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information
of ANSYS, Inc. and its subsidiaries and affiliates.