Figure 5.2: Examples of Time-Varying Loads
Suppose that you have a set of time-varying loads such as the ones shown above. There are three load
functions, so you need to define three arra y parameters. All three arra y parameters must be of type
TABLE. The force function has five points, so it needs a 5 x 1 array; the pressure function needs a 6 x 1
array; and the temperature function needs a 2 x 1 array. Notice that all three arrays are one-dimensional.
The load values are entered in column 1 and the time values are entered in column zero. ( The zeroth
column and zeroth row, which normally contain index numbers, must be changed and filled with a
monotonically increasing set of numbers if you define the arra y parameter as a TABLE.)
To define the three arra y parameters, you first need to declare their type and dimensions. T o do so, use
either of the following:
Command(s):*DIM
GUI: Utility Menu> Parameters> Array Parameters> Define/Edit
For example:
*DIM,FORCE,TABLE,5,1
*DIM,PRESSURE,TABLE,6,1
*DIM,TEMP,TABLE,2,1You can now use either the arra y parameter editor (Utility Menu> Parameters> Array Parameters>
Define/Edit) or a set of "=" commands to fill these arrays. The latter method is shown below.
FORCE(1,1)=100,2000,2000,800,100! Force values in column 1
FORCE(1,0)=0,21.5,50.9,98.7,112! Corresponding time values in column 0
FORCE(0,1)=1! Zeroth row
PRESSURE(1,1)=1000,1000,500,500,1000,1000
PRESSURE(1,0)=0,35,35.8,74.4,76,112
PRESSURE(0,1)=1
TEMP(1,1)=800,75
TEMP(1,0)=0,112
TEMP(0,1)=1You have now defined the load histories. To apply these loads and obtain the solution, you need to
construct a do-loop (using the commands DO and ENDDO) such as the one shown below:
TM_START=1E-6! Starting time (must be > 0)
TM_END=112! Ending time of the transient
TM_INCR=1.5! Time increment
*DO,TM,TM_START,TM_END,TM_INCR! Do for TM from TM_START to TM_END inRelease 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationSolution