- Select the sensitivity command. A window appears listing the models you have selected (Figure 44). Select and setup each model individually. Note that you must set up all of them in order to perform an analysis. When you select a model a window similar to that in Figure 46 appears. The highlighter bar is in the independent attribute field. If you have just run a single variable analysis, that variable will appear in this field.
- If you wish to use a different attribute Press the Space bar. A list of attributes appears for the active model. Select the attribute you want from the list. To see the current value for the available attributes use the Values hot key (Figure 47).
- Input the values for the remaining fields, which are defined below. Select Close to accept or hit Esc to cancel to return to the Sensitivity menu.
- Define the values for the fields, which are defined below. Select
Close to accept, Esc to cancel and return to the Sensitivity
screen.
Start % for X: The lowest attribute value to be used in the calculation. Enter a percentage deviation from the current value here. For example, imagine the attribute you selected in step 2 above was NU_die, which has an original value of 0.4. If you enter 0 as the Start % then your starting point is the current attribute value (0.4). If you enter 100 (i.e. 100% deviation) the calculations will begin at a value two times your original value (0.8).
End % for X: The highest attribute value, in terms of percent deviation, as described in Start %.
Number of Steps: The total number of calculations you wish to make over the range specified by the Start and End %. Note that as you increase this number, calculation time increases. However, accuracy and curve smoothness also increase.
7.3.2.3.2 The Calculate Option
After defining the function or derating curves, select Calculate. As the calculations are performed, a series of messages appear. Sometimes the calculations stop and an error message is displayed. Find the error with the Error Log option in Section 7.2.2.4.3. You return to the Derating screen when the calculations are finished.
7.3.2.3.3 The Sensitivity Command
This tool enables you to conduct an evaluation of the interactive effect of any two variables for any number of constant values of mission life.
Dependent Attribute (Y Axis): Press the Space bar to select the attribute which will be used as the y-axis variable.
Start % for X: The lowest attribute value to be used in the calculation. Enter a percentage deviation from the current value here. See the discussion on Start % in Section 7.3.2.3.1 The Function Command, for more detail.
End % for X: The highest attribute value, in terms of percent deviation, as described in Start %.
Number of Steps for X: The total number of calculations you wish to make over the range specified by the Start and End %. note that as you increase this number, calculation time increases. However, accuracy and curve smoothness also increase.
Solutions Requested: This field shows the number on function values you wish to calculate for. This field will appear as "None" until you have entered one or more values. To do this, hit Enter when "None" is highlighted and a window asking for a new function value will appear (Figure 48).
It contains a default of 1E5. Type in the first function value you wish to perform the analysis for. If you want to add more function value, hit Enter on the Solutions Requested field and a window listing all of your requests will appear. Using Add, insert additional function values into the list, see Figure 49. Use Edit to change a give value, or Delete to remove values.
