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What kinds of data results can I display for my predictions in
Lambda Predict 3?
Using Lambda Predict
3 you can display many calculated values in the System
Hierarchy panel. This makes it easy to scan through the analysis
to find the results you need to support your decisions.
You can choose which results you want to display on the
System Hierarchy page of the User Setup (File > User Setup).
The options for calculated results are:
- Failure Rate(t) displays the expected failure rate at
the mission time, t (hours), as specified in the Mission
Time field of the general properties of the top-level item.
- Failure Rate(t=INF) displays the expected failure
rate when the mission time is equal to infinity (i.e. the
steady-state failure rate).
- MTBF displays the mean time between failures, expressed
in hours.
- Contribution displays the contribution made by the item
to the failure rate of its direct parent. For example, a
value of 0.25 indicates that the item accounts for 25% of
the failure rate of its direct parent.
- Unreliability(t) displays the expected reliability at
the mission time, t (hours), as specified in the Mission
Time field of the general properties of the top-level item.
- Standard Deviation(t=INF), for Telcordia SR-332 Issue 2
systems, displays the deviation of the corresponding
steady-state failure rate. It is calculated based on the
base standard deviation specified in that standard. For more
information about this option, refer to the Lambda Predict 3
Users Guide.
- Failure Rate Upper Bound(t=INF), for Telcordia SR-332
Issue 2 systems, displays the upper confidence bound on the
steady-state failure rate. For more information about this
option, refer to the Lambda Predict 3 Users Guide.
- Early Life Factor, for Bellcore/Telcordia systems,
displays the ratio of the items early life failure rate to
its steady-state failure rate.
- Based on your inputs in the MIL217 Non Operational
window:
- Non-Operational Failure Rate, for
MIL-HBDK-217F systems, displays the failure rate, in
failures per million hours, during non-operational
phases.
- Non-Operational MTBF, for MIL-HBDK-217F
systems, displays the mean time between failures during
non-operational phases, expressed in hours.
- Non-Operational Contribution, for
MIL-HBDK-217F systems, displays contributions made by
the item to the failure rate of its direct parent during
non-operational phases.
- Derating, for systems, displays the name of the
derating standard applied or, for components, displays the status of
the component with regard to derating (i.e. whether
the component meets the derating requirements defined in the
standard , exceeds the nominal ratings but is not
overstressed, or is overstressed according to the derating
requirements).
How can I enter
classification and mode data in Data Sheets in RGA 7?
In RGA 7,
when you are using the Crow Extended model or the Crow
Extended - Continuous Evaluation model, you will need to
enter information on the failure mode that caused the
failure and the classification of each failure mode,
where:
- A indicates that no corrective action was or
will be performed (management chooses not to address
for technical, financial or other reasons).
- BC indicates that corrective action was taken
during the test or, in the case of multi-phase
analysis, at the time of failure. The analysis
assumes that the effect of the corrective action was
experienced during the test (as with other
test-fix-test reliability growth analyses.)
- BD indicates delayed corrective action. In the
case of single-phase analysis, "delayed" means at
the end of the test; in the case of multi-phase
analysis, "delayed" includes any time after the
first occurrence of the failure mode. You will be
required to define an effectiveness factor for each
BD mode to estimate the fractional decrease in
failure intensity once the fix has been applied.
There are several ways to enter this information. You
can:
- Choose the classification from the drop-down
list that appears when you click a cell in the
Classification column and manually
enter the failure mode information in the Mode
column.
- Type the classification and mode
information into their respective columns. You can type the full classification
identifier, or you can enter "C" or "D" in the
Classification column and the software will
automatically convert your entry to "BC" or "BD."
- Enter the classification and mode directly in
the Classification cell and RGA 7 will parse the
data for you. For example, if you have a BC mode
that represents a circuit failure, instead of typing
"BC" in the Classification column and "Circuit
failure" in the Mode column, you can type "dCircuit failure" in the
Classification column and then press ENTER to move out
of the cell. RGA 7 parses the data and puts "BD" in the
Classification column and "Circuit failure" in the Mode
column for you.
The last two methods also work when you are pasting
data into the Folio.
Note that each unique Mode description must have the
same classification wherever it appears in the data set (e.g. you cannot have a BC mode
called "Circuit failure" and a BD mode called "Circuit
failure"). This also applies to situations in which
the modes have been identified by number (e.g.
you cannot have a BC mode called "1" and a BD mode
called "1").
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