Transcript asent_frp

Reliability Predictions
Last revised 08/10/2005
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Introduction
The Reliability Manager is the tool in ASENT that is used to
perform a Reliability Prediction. Here, the user can define the
product tree structure and specify part lists, either by adding them
one at a time, in groups, or importing them from BOM or CAD files.
The product tree structure can be easily built in the Reliability
Manager. Tree nodes can be added, copied, moved or deleted. Entire
trees or sub-trees can be imported either from other ASENT projects
or from Excel files.
Both Operating and Non-Operating predictions can be performed.
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Overview
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Reliability Manager Screen Layout
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Invoking the Reliability Manager
To invoke the
Reliability
Manager merely
right-click on a
project and select
the Reliability
Manager menu
option.
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Reliability Mgr. Displays product tree
This screen displays the
product tree structure for
the DEMO_PRJ project.
Click on the ‘+’ symbol to
expand a branch in the tree,
and click on the ‘-’ symbol
to collapse a branch in the
tree.
When you right-click on a
item in the product tree,
then a drop-down menu
will appear.
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Reliability Mgr. Online Help Book
To pull up the online
help, select the Help
menu option and select
Contents and Index. This
will display the help
books for the active tool.
This screen shows the
user pulling up the help
books for the Reliability
Manager.
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Reliability Mgr. Online Help Book
For detailed explanations
on menu options, data
tabs and other
information associated
with the product tree,
select the Working with
the Product Tree topic.
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Importing data from other projects
The Import
Subtree option
makes
importing data
from other
projects easy. In
the slides that
follow we will
import a
MODEM card
from the
Computer
project to the
Chassis of
DEMO_PRJ.
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User selects project to import from
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Product tree for the computer project
Here, the user is presented
with the product tree
structure of the Computer
project. The user selects the
MODEM card and clicks on
the OK button in order to
import the MODEM card
from the Computer project
to the chassis of
DEMO_PRJ.
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Modem is imported to the chassis
After the import,
the MODEM card
now appears in the
chassis of
DEMO_PRJ.
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Calculate failure rates for entire system
Failure rates can be
calculated at any
level (part, board,
assembly, or the
entire system). The
following failure
rate prediction
methods are
included: 217F,
217F-1, 217F-2,
Bellcore TR-332
Issue 6, Telcordia,
and the RAC
Commercial
Practices NonOp
FR method.
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Calculate failure rates for entire system
At the system level,
the user specifies
the prediction
method,
environment, and
operating
temperature to be
used in performing
the failure rate
prediction.
Caution:
By default, lower level assemblies and boards will inherit the FR Method,
Environment and Temperature of their parent.
These
values should
NOT be entered
for lower level
assemblies or
boards unless
they are different
than the system
values.
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Calculating failure rates
Select the type of failure
rates to calculate (Operating
or Non-Operating) and click
on the Calculate button.
ASENT will then use the FR
Method that you have chosen
(i.e. If 217FN2 was selected
for Operating failure rates,
then ASENT will use MILHDBK-217F, Notice 2).
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Status flags alert user of a problem
Status Flags
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Failure Rate calculation status flags
The table below describes the meaning of the status flags that
appear in the product tree after calculating failure rates.
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Status flags pinpoint overstressed C0001
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Run troubleshooting on C0001
Below, the troubleshooting option is turned on and the failure
rate for C0001 is re-calculated.
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Run troubleshooting on C0001
After the calculation is
complete, then ‘Finished’
will be displayed below
the status bar, and the
‘View’ option at the top of
the window is now
selectable.
Select the View |
Diagnostic option to
display the troubleshooting
report.
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Troubleshooting shows voltage overstress
Here, the troubleshooting report shows that we have a
voltage overstress condition.
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Correct applied voltage for C0001
Enter a new
applied voltage
value for
C0001. Notice
that the user can
enter either a
value for the
applied voltage,
or a percent of
the rated voltage
for the part.
Here, the user
sets the applied
voltage to 50%
of the rated
voltage for the
part.
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Re-calculated failure rates are OK now
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Report Generation
Reports can be
generated from any
level in the product tree
structure. Right-click
on an item and select
the Reports option. The
Op Tree FR report is a
very common reliability
prediction report. It
generates an indentured
tree structure for the
operating failure rate of
the item.
The report can be
sorted by either failure
rate or reference
designator. It can
include both assemblies
and parts or just
assemblies only.
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Generating Prediction Reports
Below is a standard failure rate prediction report. From the report viewer, reports are printed by clicking on the
printer icon
. Reports can be saved in a wide variety of formats by clicking on the
icon.
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Failure Rate Sensitivity Analysis
ASENT’s survey tool allows
you to calculate failure rates
over a range of temperatures
to see how sensitive you
design is to increases in
temperature. From the Failure
Rate Calculator window, it is
invoked by selecting the
Temperature Scan option
from the Analyze menu.
Here, the user has selected a
starting temperature of 55
degrees C with 5 degree
increments. ASENT will
calculate the failure rates based
on 55, 60, 65, and 70 degrees.
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Failure Rate Sensitivity Analysis
The results of the temperature scan can be seen by
selecting the Survey option from the View menu.
The troubleshooting diagnostics associated with
each run can be viewed by selecting the Diagnostic
option from the View menu.
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Exporting Survey Results to Excel
These survey results can be easily exported to Excel by selecting the Export To Excel option from
the File menu.
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Mission Profiler
The Mission Profiler allows you to define profiles
that depict various operating conditions that your
product might be exposed to. From the Failure Rate
Calculator, the Mission Profiler is invoked by
selecting the Mission Profiler option from the
Analyze men.
From the Mission Profiler screen you
can either select an existing profile or
create new ones.
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Mission Profiler
Click on the icon below to
create a new profile.
New entries are made by
clicking on the
button.
Profile results
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Mission Profiler Results
Below is the Excel file showing the Mission Profile results. These results are easily exported to
Excel by selecting the Export To Excel option from the File menu.
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