Life Data and Life-Stress Data SimuMatic Setup

SimuMatic generates multiple data sets using Monte Carlo simulation. (See Monte Carlo Utility for information about how each data set is generated.) It then analyzes each data set individually (e.g., to find the reliability at a specified time) and the group of data sets as a whole (e.g., to find the average reliability at a specified time across the data sets).

To create a SimuMatic folio for life data or life-stress data, choose Home > Insert > SimuMatic and choose either the SimuMatic or Stress-Dependent SimuMatic option.

Main, Censoring and Settings Tabs

The Main, Censoring and Settings tabs of the SimuMatic setup window are the same as in the Monte Carlo Utility. The settings in these tabs determine how each data set is generated.

On the Settings tab, you must enter the Number of data sets to generate. In most cases, you will want this number to be reasonably large (e.g., 1000).

Analysis Tab

• Analysis Method and Rank Method (available in for life data only) specifies the methods to use for calculating the parameters of the simulated data sets. Select the Use RS Regression Method check box to use the ReliaSoft ranking method (RRM) for interval data. If this check box is cleared or if there is no interval data, then the software will use the standard ranking method (SRM).
• Confidence Bounds on Plots displays the specified confidence bounds in plots that are based on the generated data points. For example, if you enter 90, the plot sheet of the SimuMatic folio will display the 90% two-sided confidence bounds on the plots.

Test Design Tab (Optional)

The Test Design tab of the setup window allows you to use SimuMatic to design or evaluate a reliability test. The software will analyze the data sets in order to estimate the time at which the product would have a specified reliability (i.e., the demonstrated life). This value can help you determine the combination of test time and sample size that will be adequate to demonstrate a required reliability target at a specified confidence level.

Note: The software calculates the demonstrated time by taking each data set and solving for the time at which the specified target reliability would be reached. It then orders these time values to find the time value that corresponds to your specified confidence level. For example, if you enter 85 for the target reliability and 90 for the confidence level, the software will, for each data set, solve for the time at which a product described by that data set's model would have a reliability of 85%. It would then order the calculated time values and locate the value in the 10th percentile, which is reported as the 90% lower one-sided confidence bound for the demonstrated time.

Reliabilities and Times Tab (Optional)

The Reliabilities and Times tab of the setup window allows you to calculate the time for every given reliability, and/or calculate the reliability for every given time. You can enter up to 10 reliability values (as decimals less than 1) and up to 10 time values.

For example, if you enter 0.5 in the Reliabilities area, the data sheets in the SimuMatic folio will display the estimated time when the reliability will be equal to 50%. If you enter 100 in the Times area, the reliability at time 100 will be displayed.