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We have compiled some case studies to demonstrate the
types of analyses that you will be able to perform with ReliaSoft's
Weibull++ 7 life data analysis software.
For the actual case studies, the data and/or exact test
method that were used may have been modified in cases where the actual
information was deemed to be confidential.
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Examples Using Standard
Folios |
| Case
Study 1:
Complete and
Right Censored Data Analysis |
Description
Ten identical units are reliability tested at the same
application and operation stress levels for 120 hr. The objective
is
to use the complete and right censored data from the test to determine the
unreliability for a mission duration of 226 hr and the warranty time for a
reliability of 85%.
Review
Study...
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| Case
Study
2:
Analyzing
Complete Data |
Description
Six units are tested to failure. The objective is to use the complete data from the
test to obtain a probability
plot with 90%, 2-sided confidence bounds and a pdf
plot.
Review
Study...
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| Case
Study
3:
Analyzing
Sudden Death Data |
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Description
A manufacturer uses data from a sudden death test to demonstrate
the reliability for a product with a 70% lower one-sided confidence
level. Four groups of five units each are tested sequentially until
the first failure in each group.
Review
Study...
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| Examples
Using Specialized Folios |
| Case
Study 4:
Degradation
Analysis Example |
Description
Five
turbine blades were tested for crack propagation. The test
units were cyclically stressed and inspected every 100,000 cycles
for crack length. Failure is defined as a crack of length 30 mm or
greater.
Review
Study...
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Case
Study
5:
Warranty
Analysis |
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Description
A company keeps track of its shipments and warranty returns on
a month-by-month basis. Using the Warranty Analysis module, determine the
parameters for a 2-parameter Weibull distribution and predict the
number of products from each of the three shipment periods that will
be returned under warranty in October.
Review
Study...
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Case
Study
6:
Factory Equipment
Failure Log |
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Description
A manufacturer is tracking the failures occurring in the
product line. When a failure occurs in a machine, the time of
occurrence and the time of repair are recorded for the machine and
the parts that failed. Using Weibull++’s Event Log, determine the
failure and repair distributions.
Review
Study...
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Case
Study
7:
Non-Parametric Life
Data Analysis |
Description
A group of 55 units are put on a life test during which the units
are evaluated every 50 hours. Use the simple actuarial method to
determine reliability estimates for each failure time.
Review
Study... |
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Case
Study
8:
Non-Parametric
Recurrence Data Analysis for Transmission Repair |
Description
Repairs are tracked on automatic transmissions in a sample
of 34 cars in a preproduction road test. The objective is to
determine the mean cumulative number of repairs per car
by 24,000 test miles (equivalently
5.5 x 24,000 = 132,000 customer miles).
Review
Study... |
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Case
Study
9:
Parametric
Recurrence Data Analysis Example |
Description
The repairs made to a system are tracked over a period of time.
Each repair is capable of addressing any damage accumulated up to the
time of the current failure.
The objective is to determine how effective the repairs are.
Review
Study... |
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Further
Examples |
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Case
Study 10:
Competing
Failure Modes Analysis |
Description
An electronic component has two failure modes. One failure mode is
due to random voltage spikes, which cause failure by overloading the
system. The other failure mode is due to wear-out failures, which
usually happen only after the system has run for many cycles. Using
competing failure modes analysis, the
overall reliability for the component at 100,000 cycles is determined.
Review
Study...
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Case
Study 11:
Failure Modes RBD Analysis |
Description
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.
Review
Study...
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Guest
Submission Case Studies
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In addition to the case studies prepared by ReliaSoft personnel, we
welcome contributions from the reliability community. To
share information about your life data analysis
techniques with your colleagues, submit your findings for
incorporation into our collection of "Guest Submission Case
Studies." |
Contact
the Webmaster with
questions or comments regarding these case studies. |
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Version 7
