diff --git a/presentations/fmea/fmea_pres.tex b/presentations/fmea/fmea_pres.tex index 9a82ffc..338f6fc 100644 --- a/presentations/fmea/fmea_pres.tex +++ b/presentations/fmea/fmea_pres.tex @@ -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} diff --git a/style.tex b/style.tex index 319661a..75affc6 100644 --- a/style.tex +++ b/style.tex @@ -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}