Weibull++ Example 11 - Failure Modes RBD Analysis
Background
A particular component can fail due to six independent primary failure modes: A, B, C, D, E and F. The component fails if mode A, B or C occurs. If mode D, E or F occurs alone, the component does not fail; however, the component will fail if any two (or more) of these modes occur (i.e. D and E; D and F; E and F). The objective is to analyze each data set using the 2-parameter Weibull distribution with MLE and to determine the lower 1-sided 90% confidence interval on the reliability of this component at 100 hr.
Experiment and Data
The following tables present the time-to-failure data for these modes (in hr).
|
Mode A |
Mode B | Mode C | ||||||||
|
Number |
State | Time |
Number |
State | Time |
Number |
State | Time | ||
| 1 | F | 1144 | 1 | F | 19 | 1 | F | 2221 | ||
| 1 | F | 1719 | 1 | F | 140 | 1 | F | 2257 | ||
| 1 | F | 2129 | 1 | F | 292 | 1 | F | 2569 | ||
| 1 | F | 2803 | 1 | F | 432 | 1 | F | 3029 | ||
| 1 | F | 3020 | 1 | F | 528 | 1 | F | 3805 | ||
| 1 | F | 3082 | 1 | F | 552 | 10 | S | 5000 | ||
| 1 | F | 3589 | 1 | F | 605 | |||||
| 1 | F | 3973 | 1 | F | 734 | |||||
| 1 | F | 4337 | 1 | F | 779 | |||||
| 1 | F | 5011 | 1 | F | 874 | |||||
| 1 | F | 5029 | ||||||||
| 18 | S | 5500 | ||||||||
|
Mode D |
Mode E | Mode F | ||||||||
|
Number |
State | Time |
Number |
State | Time |
Number |
State | Time | ||
| 1 | F | 1063 | 1 | F | 1290 | 1 | F | 605 | ||
| 1 | F | 1085 | 1 | F | 2261 | 1 | F | 760 | ||
| 1 | F | 1399 | 1 | F | 2355 | 1 | F | 773 | ||
| 1 | F | 1445 | 1 | F | 3209 | 1 | F | 854 | ||
| 1 | F | 1550 | 1 | F | 3284 | 1 | F | 890 | ||
| 1 | F | 2056 | 1 | F | 3394 | 1 | F | 1165 | ||
| 1 | F | 4384 | 1 | F | 3596 | 1 | F | 1220 | ||
| 1 | F | 4863 | 1 | F | 4203 | 1 | F | 1320 | ||
| 8 | S | 5000 | 1 | F | 4254 | 1 | F | 1967 | ||
| 1 | F | 4294 | 1 | F | 2606 | |||||
| 1 | F | 4420 | 1 | F | 2834 | |||||
| 10 | S | 5000 | 15 | S | 3000 | |||||
Analysis
Step 1: Using Weibull++ 7, the first step is to create a new Data Entry Spreadsheet to hold grouped times-to-failure data with suspensions.
Step 2: Rename the Folio to "Component" and the Data Sheet to "A", enter the data given for Failure Mode A and use the 2-parameter Weibull distribution with MLE to calculate the parameters, as shown next.
Step 3: Insert another data sheet of the same type named "B," enter the data given for Failure Mode B and calculate the parameters. Repeat for the remaining failure modes.
Step 4: Select Add Diagram from the Project menu to add a Diagram to the project that contains a template block for each data sheet in the project, as shown next.
Step 5: Build the RBD that describes the reliability-wise configuration of the failure modes, as shown next.
Step 6: Click Calculate to analyze the Diagram, then use the Quick Calculation Page to calculate the reliability at 100 hr with the lower 1-sided 90% confidence bound, as shown next.
The lower bound is estimated to be 82.23%.
