The sample data file TurbineEngineDesign2.jmp, found in the Reliability subfolder, contains data on failures for a turbine engine design over three phases of a testing program. The first two columns give time intervals during which failures occurred. These intervals are recorded as days since the start of testing. The exact failure times are not known; it is only known that failures occurred within these intervals.
1.
Open the TurbineEngineDesign2.jmp sample data table.
2.
Select Analyze > Reliability and Survival > Reliability Growth.
3.
On the Time to Event Format tab, select the columns Interval Start and Interval End, and click Time to Event.
4.
Select Fixes and click Event Count.
5.
Select Design Phase and click Phase.
6.
7.
The Cumulative Events plot from the Observed Data report is shown in Cumulative Events Plot. The vertical dashed blue lines indicate the phase transition points. The first occurrence of Revised in the column Design Phase is in row 14. So, the start of the Revised phase is taken to be the Interval Start value in row 14, namely, day 91. Similarly, the first occurrence of Final in the column Design Phase is in row 23. So, the start of the Final phase is taken to be the Interval Start value in row 23, namely, day 200.
Cumulative Events Plot
The Piecewise Weibull NHPP report is found under the Models outline node (MTBF Plot). Here we see the mean time between failures increasing over the three phases. From the Estimates report, we see that the estimates of beta decrease over the three testing phases.
MTBF Plot
The file BrakeReliability.jmp, found in the Reliability subfolder, contains data on fixes to a braking system. The Date column gives the dates when Fixes, given in the second column, were implemented. For this data, the failure times are known. Note that the Date column must be in ascending order.
The test start time is the first entry in the Date column, 09/29/2011, and the corresponding value for Fixes is set at 0. This is needed in order to convey the start time for testing. Had there been a nonzero value for Fixes in this first row, the corresponding date would have been treated as the test start time, but the value of Fixes would have been treated as 0 in the analysis.
The test termination time is given in the last row as 05/31/2012. Because the value in Fixes in the last row is 0, the test is considered to be time terminated on 5/31/2012. Had there been a nonzero value for Fixes in this last row, the test would have been considered failure terminated.
1.
Open the BrakeReliability.jmp sample data table.
2.
Select Analyze > Reliability and Survival > Reliability Growth.
3.
Select the Dates Format tab.
4.
Select Date and click Timestamp.
5.
Select Fixes and click Event Count.
6.
Cumulative Events Plot with Crow AMSAA Model
8.
From the red triangle menu at Reliability Growth, select Fit Model > Piecewise Weibull NHPP Change Point Detection.
Cumulative Events Plot with Two Models