lunchtime edit (geddit!)

This commit is contained in:
Robin Clark 2011-10-04 15:14:19 +01:00
parent 064c85549f
commit 4917d6a199
2 changed files with 23 additions and 13 deletions

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@ -5,6 +5,16 @@
\author{Robin Clark -- Energy Technology Control Ltd}
\institute{Brighton University}
\setbeamertemplate{footline}[page number]
\newcommand{\fg}{\em functional~group}
\newcommand{\fgs}{\em functional~groups}
\newcommand{\dc}{\em derived~component}
\newcommand{\dcs}{\em derived~components}
\newcommand{\bc}{\em base~component}
\newcommand{\bcs}{\em base~components}
\newcommand{\irl}{in~real~life}
\begin{document}
\section{F.M.E.A.}
@ -79,8 +89,8 @@ For the sake of example let us choose resistor R1 in the OP-AMP gain circuitry.
\frametitle{FMEA Example: Milli-volt reader}
\begin{itemize}
\pause \item \textbf{F - Failures of given component} The resistor could fail by going OPEN or SHORT (EN298 definition).
\pause \item \textbf{M - Failure Mode} Consider the component failure mode OPEN
\pause \item \textbf{E - Effects} This will disconnect the feedback loop in the amplifier, driving the minus input HIGH causing a LOW READING
\pause \item \textbf{M - Failure Mode} Consider the component failure mode SHORT
\pause \item \textbf{E - Effects} This will drive the minus input HIGH causing a LOW OUTPUT/READING
\pause \item \textbf{A - Analysis} The reading will be out of normal range, and we will have an erroneous milli-volt reading
\end{itemize}
\end{frame}
@ -128,7 +138,7 @@ $cfm$ is the number of failure modes per component.
\begin{frame}
\frametitle{Rigorous Single Failure FMEA}
This would mean an order of $N^2$ number of checks to perform
to perform `rigorous~FMEA'. Even small systems have typically
to undertake a `rigorous~FMEA'. Even small systems have typically
100 components, and they typically have 3 or more failure modes each.
$100*99*3=29,700$.
\end{frame}
@ -352,7 +362,7 @@ and allows diagnostic mitigation for self checking etc.
It provides guidelines for the design and architecture
of computer/software systems for the four levels of
safety Integrity.
For Hardware
%For Hardware
FMEDA does force the user to consider all components in a system
by requiring that a MTTF value is assigned for each failure~mode.
@ -544,11 +554,11 @@ judged to be in critical sections of the product.
The FMMD methodology breaks the analysis down into small stages,
by making the analyst choose functional groups of components, to which FMEA is applied.
When analysed, a set of symptoms of failure for the functional group is used create a derived~component.
The derived components failure modes, are the symptoms of the functional group
by making the analyst choose {\fgs} of components, to which FMEA is applied.
When analysed, a set of symptoms of failure for the {\fg} is used create a derived~component.
The derived components failure modes, are the symptoms of the {\fg}
from which it was derived.
We can use derived components to form `higher~level' functional groups.
We can use derived components to form `higher~level' {\fgs}.
This creates an analysis hierarchy.
\end{frame}
@ -557,17 +567,17 @@ This creates an analysis hierarchy.
\begin{frame}
\frametitle{FMMD - Example}
We can take groups of components that perform a well defined task, and analyse their failure mode behaviour.
We can call these 'functional groups'.
We can call these `{\fgs}'.
If we analyse the failure mode behaviour of a functional group we can determine how it will fail, or its symptoms of failure.
We can represent this by a 'derived component', where its failure modes are the symptoms of the functional group it was derived from.
If we analyse the failure mode behaviour of a {\fg} we can determine how it will fail, or its symptoms of failure.
We can represent this by a '{\dc}', where its failure modes are the symptoms of the {\fg} it was derived from.
\end{frame}
\begin{frame}
\frametitle{FMMD - Example}
We can begin to analyse this by looking for functional groups.
The resistors would together to perform a fairly common function in electronics, that of the potential divider.
We can now take the failure modes for the resistors (OPEN and SHORT EN298) and see what effect each of these failures will have on the functional group
We can now take the failure modes for the resistors (OPEN and SHORT EN298) and see what effect each of these failures will have on the {\fg}
\end{frame}

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@ -25,7 +25,7 @@
\newcommand{\dcs}{\em derived~components}
\newcommand{\bc}{\em base~component}
\newcommand{\bcs}{\em base~components}
\newcommand{\irl}{in real life}
\newcommand{\irl}{in~real~life}
\newcommand{\enc}{\ensuremath{\stackrel{enc}{\longrightarrow}}}
\newcommand{\pin}{\ensuremath{\stackrel{pi}{\longleftrightarrow}}}
%\newcommand{\pic}{\em pure~intersection~chain}