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This example compares the results for test-fix-find-test data.
Reference Case
MIL-HDBK-189A, Section 7.5.2, pg. 206, 2009.
For this example, the following will be calculated:
- Parameters of the Crow Extended model
- Demonstrated MTBF (DMTBF)
- BD mode parameters
- Projected MTBF (PMTBF)
Data
The following table shows the data.
Failure Time
|
Classification Mode
|
0.7 |
BC1
|
3.7 |
BC1
|
13.2 |
BC1
|
15 |
BD1
|
17.6 |
BC2
|
25.3 |
BD2
|
47.5 |
BD3
|
54 |
BD4
|
54.5 |
BC3
|
56.4 |
BD5
|
63.6 |
A
|
72.2 |
BD5
|
99.2 |
BC4
|
99.6 |
BD6
|
100.3 |
BD7
|
102.5 |
A
|
112 |
BD8
|
112.2 |
BC5
|
120.9 |
BD2
|
121.9 |
BC6
|
125.5 |
BD9
|
133.4 |
BD10
|
151 |
BC7
|
163 |
BC8
|
164.7 |
BD9
|
174.5 |
BC9
|
177.4 |
BD10
|
191.6 |
BC10
|
192.7 |
BD11
|
213 |
A
|
244.8 |
A
|
249 |
BD12
|
250.8 |
A
|
260.1 |
BD1
|
263.5 |
BD8
|
271.1 |
A
|
274.7 |
BD6
|
282.8 |
BC11
|
285 |
BD13
|
304 |
BD9
|
315.4 |
BD4
|
317.1 |
A
|
320.6 |
A
|
324.5 |
BD12
|
324.9 |
BD10
|
342 |
BD5
|
350.2 |
BD3
|
355.2 |
BC12
|
364.6 |
BD10
|
364.9 |
A
|
366.3 |
BD2
|
373 |
BD8
|
379.4 |
BD14
|
389 |
BD15
|
394.9 |
A
|
395.2 |
BD16
|
Termination Time = 400 hours
BD Mode
|
EF
|
1 |
0.67
|
2 |
0.72
|
3 |
0.77
|
4 |
0.77
|
5 |
0.77
|
6 |
0.87
|
7 |
0.92
|
8 |
0.50
|
9 |
0.85
|
10 |
0.89
|
11 |
0.70
|
12 |
0.63
|
13 |
0.64
|
14 |
0.72
|
15 |
0.69
|
16 |
0.46
|
Result
The book has the following results:
- Beta = 0.9103, Lambda = 0.2397
- BD Mode Parameters: Beta = 0.7472, Lambda = 0.1820
Results in RGA
In RGA, the Crow Extended model with the maximum likelihood estimation (MLE) method was used to calculate the results.
- The model parameters are:
- The PMTBF is 11.29 hours, as shown in the plot: