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Robin Clark 2013-09-25 19:27:55 +01:00
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18
submission_thesis/CH2_FMEA/copy.tex
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@ -193,7 +193,7 @@ typically of the form of examining scenarios such as
%are examined. %are examined.
% %
% %
FMD-91 is a reference document released into the public domain by the United States DOD FMD-91~\cite{fmd91} is a reference document released into the public domain by the United States DOD
and describes `failures' of common electronic components, with percentage statistics for each failure. and describes `failures' of common electronic components, with percentage statistics for each failure.
% %
FMD-91 entries include general descriptions of internal failures alongside {\fms} of use to an FMEA investigation. FMD-91 entries include general descriptions of internal failures alongside {\fms} of use to an FMEA investigation.
@ -418,7 +418,7 @@ For Op-Amp failures modes, FMD-91\cite{fmd91}{3-116] states,
These are mostly internal causes of failure, more of interest to the component manufacturer These are mostly internal causes of failure, more of interest to the component manufacturer
than a test engineer % designer than a test engineer % designer
looking for the symptoms of failure. looking for symptoms of failure.
% %
These failure causes within the Op-Amp need to be translated to symptomatic {\fms}. These failure causes within the Op-Amp need to be translated to symptomatic {\fms}.
% %
@ -570,13 +570,13 @@ $$ fm(OPAMP) = \{ LOW, HIGH, NOOP, LOW\_SLEW \} . $$
The EN298 pinouts failure mode technique cannot reveal failure modes due to internal failures, The EN298 pinouts failure mode technique cannot reveal failure modes due to internal failures,
and that is why it misses the $LOW\_SLEW$. and that is why it misses $LOW\_SLEW$.
% %
The FMD-91 entries for op-amps are not directly usable as The FMD-91 entries for op-amps are not directly usable as
component {\fms} in FMEA and require interpretation. component {\fms} in FMEA and require interpretation.
% %
However, once a failure mode analysis has been carried out, the model can However, once a failure mode determination has been carried out, the model can
be used throughout the FMEA process. be re-used throughout the FMEA process.
%%%% Talk about R differences ?? XXXXX %%%% Talk about R differences ?? XXXXX
@ -734,7 +734,7 @@ the circuit behaviour is measured in finer granularity,
% %
With this style of fault finding, because it is based on experiment, With this style of fault finding, because it is based on experiment,
hopping from module to module eliminating working ones, until hopping from module to module eliminating working ones, until
failure is found~\cite{maikowski}, it is efficient in terms of failure is found~\cite{maikowski}, is efficient in terms of
concentrating effort. concentrating effort.
% %
The rationale and work-culture of those tasked to The rationale and work-culture of those tasked to
@ -985,7 +985,7 @@ deduced).
\fmmdglossRD \fmmdglossRD
Reasoning distance, is the number of stages of logic and reasoning used Reasoning distance, is the number of stages of logic and reasoning used
in {\fm} analysis to map a failure cause to its potential outcomes; counted in {\fm} analysis to map a failure cause to its potential outcomes; counted
by th number of {\fm} to component checks made. by the number of {\fm} to component checks made.
% %
The basic FMEA example in section~\ref{basicfmea} The basic FMEA example in section~\ref{basicfmea}
considered one {\fm} against some of the components in the milli-volt reader. considered one {\fm} against some of the components in the milli-volt reader.
@ -1153,7 +1153,7 @@ cost, problems to be addressed in product production.
It generally focuses on known problems and using their It generally focuses on known problems and using their
statistical frequency %they occur statistical frequency %they occur
and their cost to fix multiplied gives a Risk Priority Number (RPN) and their cost to fix multiplied gives a Risk Priority Number (RPN)
number for the germane component {\fm}. for the germane component {\fm}.
% %
Fixing problems with the highest RPN number Fixing problems with the highest RPN number
will return most cost benefit~\cite{bfmea}. will return most cost benefit~\cite{bfmea}.
@ -1274,7 +1274,7 @@ The highest $C_m$ values would represent the most dangerous or serious
system level failures. system level failures.
The highest $C_m$ values would be at the top of a `to~fix' list The highest $C_m$ values would be at the top of a `to~fix' list
for a project manager, and some levels of risk may be considered unacceptable for a project manager, and some levels of risk may be considered unacceptable
and require re-design of some systems. and require re-design. % of some systems.
\fmmdglossFMECA \fmmdglossFMECA
\section{FMEDA - Failure Modes Effects and Diagnostic Analysis} \section{FMEDA - Failure Modes Effects and Diagnostic Analysis}