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More work on hard sell at the end

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presentations/fmea/fmea_pres.tex
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@ -239,6 +239,21 @@ will return most cost benefit.
http://www.youtube.com/watch?v=rcNeorjXMrE http://www.youtube.com/watch?v=rcNeorjXMrE
\end{frame} \end{frame}
\section{FMECA - Failure Modes Effects and Criticallity Analysis}
\begin{frame}
\frametitle{ FMECA - Failure Modes Effects and Criticallity Analysis}
\begin{figure}
\centering
\includegraphics[width=100pt]{./military-aircraft-desktop-computer-wallpaper-missile-launch.jpg}
% military-aircraft-desktop-computer-wallpaper-missile-launch.jpg: 1024x768 pixel, 300dpi, 8.67x6.50 cm, bb=0 0 246 184
\caption{Military Aircraft}
\label{fig:f16missile}
\end{figure}
Emphasis on determining criticallity of failure.
Applies some baysian statistics (probabilities of component failues and those causing given system level failures).
\end{frame}
\section{FMECA - Failure Modes Effects and Criticallity Analysis} \section{FMECA - Failure Modes Effects and Criticallity Analysis}
@ -292,6 +307,17 @@ for a project manager.
\section{FMEDA - Failure Modes Effects and Diagnostic Analysis} \section{FMEDA - Failure Modes Effects and Diagnostic Analysis}
\begin{frame}
\frametitle{ FMEDA - Failure Modes Effects and Diagnostic Analysis}
\begin{figure}
\centering
\includegraphics[width=200pt]{./SIL.jpg}
% SIL.jpg: 350x286 pixel, 72dpi, 12.35x10.09 cm, bb=0 0 350 286
\caption{SIL requirements}
\end{figure}
\end{frame}
\begin{frame} \begin{frame}
\frametitle{ FMEDA - Failure Modes Effects and Diagnostic Analysis} \frametitle{ FMEDA - Failure Modes Effects and Diagnostic Analysis}
FMEDA is the methodology behind statistical (safety integrity level) FMEDA is the methodology behind statistical (safety integrity level)
@ -337,14 +363,16 @@ $$ DiagnosticCoverage = \Sigma\lambda_{DD} / \Sigma\lambda_D $$
\begin{frame} \begin{frame}
\frametitle{ FMEDA - Failure Modes Effects and Diagnostic Analysis} \frametitle{ FMEDA - Failure Modes Effects and Diagnostic Analysis}
The diagnostic coverage for safe failures, where $\Sigma\lambda_{SD}$ represents the percentage of The \textbf{diagnostic coverage} for safe failures, where $\Sigma\lambda_{SD}$ represents the percentage of
safe detected base component failure modes, safe detected base component failure modes,
and $\Sigma\lambda_S$ the total number of safe base component failure modes, and $\Sigma\lambda_S$ the total number of safe base component failure modes,
is given as is given as
$$ SF = \frac{\Sigma\lambda_{SD}}{\Sigma\lambda_S} $$ $$ SF = \frac{\Sigma\lambda_{SD}}{\Sigma\lambda_S} $$
\end{frame}
\begin{frame}
\frametitle{ FMEDA - Failure Modes Effects and Diagnostic Analysis}
\textbf{Safe Failure Fraction.} \textbf{Safe Failure Fraction.}
A key concept in FMEDA is Safe Failure Fraction (SFF). A key concept in FMEDA is Safe Failure Fraction (SFF).
This is the ratio of safe and dangerous detected failures This is the ratio of safe and dangerous detected failures
@ -404,7 +432,7 @@ part of product approval for many regulated products in the EU and the USA...
\section{FMEA used for Safety Critical Approvals} \section{FMEA used for Safety Critical Approvals}
\begin{frame} \begin{frame}
\frametitle{Safety Critical Approvals FMEA} \frametitle{DESIGN FMEA: Safety Critical Approvals FMEA}
Experts from Approval House and Equipment Manufacturer Experts from Approval House and Equipment Manufacturer
discuss selected component failure modes discuss selected component failure modes
judged to be in critical sections of the product. judged to be in critical sections of the product.
@ -420,7 +448,7 @@ judged to be in critical sections of the product.
\end{frame} \end{frame}
\begin{frame} \begin{frame}
\frametitle{Safety Critical Approvals FMEA} \frametitle{DESIGN FMEA: Safety Critical Approvals FMEA}
\begin{figure}[h] \begin{figure}[h]
\centering \centering
@ -433,7 +461,7 @@ judged to be in critical sections of the product.
\begin{itemize} \begin{itemize}
\pause \item Impossible to look at all component failures let alone apply FMEA rigorously. \pause \item Impossible to look at all component failures let alone apply FMEA rigorously.
\pause \item In practise, failure scenarios for critical sections are contested, and either justified or extra safety measures implemented. \pause \item In practise, failure scenarios for critical sections are contested, and either justified or extra safety measures implemented.
\pause \item Meeting notes or minutes only. \pause \item Often Meeting notes or minutes only. Unusual for detailed arguments to be documented.
\end{itemize} \end{itemize}
\end{frame} \end{frame}
@ -472,7 +500,7 @@ judged to be in critical sections of the product.
\end{frame} \end{frame}
\section{Failure Mode Modular De-Composition} \section{Failure Mode Modular De-Composition}
\begin{frame} \begin{frame}
\frametitle{FMMD - Failure Mode Modular De-Composition}
% Consider the FMEA type methodologies % Consider the FMEA type methodologies
% where we look at all the failure modes in a system, and then % where we look at all the failure modes in a system, and then
% see how they can affect all other components within it, % see how they can affect all other components within it,
@ -492,31 +520,42 @@ judged to be in critical sections of the product.
The FMMD methodology breaks the analysis down into small stages, The FMMD methodology breaks the analysis down into small stages,
by making the analyst choose functional groups of components, to which FMEA is applied. by making the analyst choose functional groups of components, to which FMEA is applied.
When analysed, we will have a set of symptoms of failure for the functional group. When analysed, a set of symptoms of failure for the functional group is used create a derived~component.
We can then create a derived~component, The derived components failure modes, are the symptoms of the functional group
to represent the functional group. 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' functional groups.
This creates an analysis hierarchy. This creates an analysis hierarchy.
This addresses the state explosion (where $O$ is order
of complexity) $O=N^2$ inherent in equation~\ref{eqn:fmea_state_exp}.
\end{frame} \end{frame}
\begin{frame} \begin{frame}
\frametitle{FMMD - Failure Mode Modular De-Composition}
We can view the functional groups in FMMD as forming a hierarchy. We can view the functional groups in FMMD as forming a hierarchy.
If for the sake of example we consider each functional group to If for the sake of example we consider each functional group to
be three components, the figure below shows be three components, the figure below shows
how the levels work and converge to a top or system level. how the levels work and converge to a top or system level.
\begin{figure}
% \begin{figure} \centering
% \centering \includegraphics[width=300pt]{./three_tree.png}
% \includegraphics[width=300pt]{./three_tree.png} % three_tree.png: 780x226 pixel, 72dpi, 27.52x7.97 cm, bb=0 0 780 226
% % three_tree.png: 780x226 pixel, 72dpi, 27.52x7.97 cm, bb=0 0 780 226 \caption{Functional Group Tree example}
% \caption{Functional Group Tree example} \label{fig:three_tree}
% \label{fig:three_tree} \end{figure}
% \end{figure}
\end{frame} \end{frame}
\begin{frame}
\frametitle{FMMD - Failure Mode Modular De-Composition}
The fact FMMD analyses small groups of components at a time, and organises them
into a hierarchy
addresses the state explosion (where $O$ is order
of complexity) $O=N^2$ inherent in equation
\begin{equation}
\label{eqn:fmea_single2}
N.(N-1).cfm % \\
%(N^2 - N).cfm
\end{equation}
We can represent the number of failure scenarios to check in an FMMD hierarchy We can represent the number of failure scenarios to check in an FMMD hierarchy
with equation~\ref{eqn:anscen}. with equation~\ref{eqn:anscen}.
@ -524,49 +563,58 @@ with equation~\ref{eqn:anscen}.
\label{eqn:anscen} \label{eqn:anscen}
\sum_{n=0}^{L} {fgn}^{n}.fgn.cfm.(fgn-1) \sum_{n=0}^{L} {fgn}^{n}.fgn.cfm.(fgn-1)
\end{equation} \end{equation}
Where $fgn$ is the number of components in each functional group, Where $fgn$ is the number of components in each functional group,
and $cfm$ is the number of failure modes per component and $cfm$ is the number of failure modes per component
and L is the number of levels, the number of and L is the number of levels, the number of
analysis scenarios to consider is show in equation~\ref{eqn:anscen}. analysis scenarios to consider is show in equation~\ref{eqn:anscen}.
~\ref{eqn:fmea_state_exp}.
So for a very simple analysis with three components forming a functional group where \end{frame}
each component has three failure modes, we have only one level (zero'th).
So to check every failure modes against the other components in the functional group
requires 18 checks.
\begin{equation}
\label{eqn:anscen2}
\sum_{n=0}^{0} {3}^{0}.3.3.(3-1) = 18
\end{equation}
\clearpage
In other words, we have three components in our functional group, % So for a very simple analysis with three components forming a functional group where
and nine failure modes to consider. % each component has three failure modes, we have only one level (zero'th).
So taking each failure mode and looking at how that could affect the functional group, % So to check every failure modes against the other components in the functional group
we must compare each failure mode against the two other components (the `$fgn-1$' term). % requires 18 checks.
%
For the one `zero' level FMMD case we are doing the same thing as FMEA type analysis % \begin{equation}
(but on a very simple small sub-system). % \label{eqn:anscen2}
We are looking at how each failure~mode can effect the system/top level. % \sum_{n=0}^{0} {3}^{0}.3.3.(3-1) = 18
We can use equation~\ref{eqn:fmea_state_exp44} to represent % \end{equation}
the number of checks to rigorously perform FMEA, where $N$ is the total % \clearpage
number of components in the system, and $cfm$ is the number of failures per component. %
%
%
% In other words, we have three components in our functional group,
% and nine failure modes to consider.
% So taking each failure mode and looking at how that could affect the functional group,
% we must compare each failure mode against the two other components (the `$fgn-1$' term).
%
% For the one `zero' level FMMD case we are doing the same thing as FMEA type analysis
% (but on a very simple small sub-system).
% We are looking at how each failure~mode can effect the system/top level.
% We can use equation~\ref{eqn:fmea_state_exp44} to represent
% the number of checks to rigorously perform FMEA, where $N$ is the total
% number of components in the system, and $cfm$ is the number of failures per component.
%
Where $N=3$ and $cfm=3$ we can see that the number of checks for this simple functional % Where $N=3$ and $cfm=3$ we can see that the number of checks for this simple functional
group is the same for equation~\ref{eqn:fmea_state_exp22} % group is the same for equation~\ref{eqn:fmea_state_exp22}
and equation~\ref{eqn:anscen}. % and equation~\ref{eqn:anscen}.
\clearpage % \clearpage
%\section{Example} %\section{Example}
\begin{frame}
To see the effects of reducing `state~explosion' we need to look at a larger system. \frametitle{FMMD - Failure Mode Modular De-Composition}
Let us take a system with 3 levels and apply these formulae. To see the effects of reducing `state~explosion' we can use an example.
% with fixed numbers
%for components in a functional group, and failure modes per component.
Let us take a system with 3 levels,
with three components per functional group and three failure modes per component,
and apply these formulae.
Having three levels (in addition to the top zero'th level) Having three levels (in addition to the top zero'th level)
will require 81 base level components. will require 81 base level components.
@ -584,7 +632,11 @@ $$
\sum_{n=0}^{3} {3}^{n}.3.3.(2) = 720 \sum_{n=0}^{3} {3}^{n}.3.3.(2) = 720
%\end{equation} %\end{equation}
$$ $$
\end{frame}
\begin{frame}
\frametitle{FMMD - Failure Mode Modular De-Composition}
Thus for FMMD we needed to examine 720 failure mode scenarios, and for traditional FMEA Thus for FMMD we needed to examine 720 failure mode scenarios, and for traditional FMEA
type analysis methods 19440. type analysis methods 19440.
% In practical example followed through, no more than 9 components have ever been required for a functional % In practical example followed through, no more than 9 components have ever been required for a functional
@ -593,13 +645,16 @@ type analysis methods 19440.
% and 12 failure modes per component) and apply the formulas for a 4 level analysis % and 12 failure modes per component) and apply the formulas for a 4 level analysis
% (i.e. % (i.e.
\clearpage \end{frame}
\begin{frame}
\frametitle{FMMD - Failure Mode Modular De-Composition}
Note that for all possible double simultaneous failures the equation~\ref{eqn:fmea_state_exp} becomes Note that for all possible double simultaneous failures the equation~\ref{eqn:fmea_state_exp} becomes
equation~\ref{eqn:fmea_state_exp2} essentially making the order $N^3$. equation~\ref{eqn:fmea_state_exp2} essentially making the order $N^3$.
The FMMD case (equation~\ref{eqn:anscen2}), is cubic within the functional groups only, The FMMD case (equation~\ref{eqn:anscen2}), is cubic within the functional groups only,
not all the components in the system. not all the components in the system.
\begin{equation} \begin{equation}
\label{eqn:fmea_state_exp2} \label{eqn:fmea_state_exp2}
N.(N-1).(N-2).cfm % \\ N.(N-1).(N-2).cfm % \\
@ -610,6 +665,53 @@ not all the components in the system.
\label{eqn:anscen2} \label{eqn:anscen2}
\sum_{n=0}^{L} {fgn}^{n}.fgn.cfm.(fgn-1).(fgn-2) \sum_{n=0}^{L} {fgn}^{n}.fgn.cfm.(fgn-1).(fgn-2)
\end{equation} \end{equation}
\end{frame}
\begin{frame}
\frametitle{FMMD - Failure Mode Modular De-Composition}
\textbf{traceability}
Because each reasoning stage contains associations ($FailureMode \mapsto Sypmtom$)
we can trace the `reasoning' from base level component failure mode to top level/system
failure.
\end{frame}
\begin{frame}
\frametitle{FMMD - Failure Mode Modular De-Composition}
\textbf{re-usability}
Electronic Systems use commonly re-used functional groups (such as potential~dividers, amplifier configurations etc)
Once a derived component is determined, it can generally be used in other projects.
\end{frame}
\begin{frame}
\frametitle{FMMD - Failure Mode Modular De-Composition}
\textbf{total coverage}
With FMMD we can ensure that all component failure modes
have been represented as a symptom in the derived components created from them.
We can thus apply automated checking to ensure that no
failure modes, from base or derived components have been
missed in an analysis.
\end{frame}
\begin{frame}
\frametitle{FMMD - Failure Mode Modular De-Composition}
\textbf{Conclusion: FMMD}
\begin{itemize}
\pause \item Addresses State Explosion
\pause \item Addresses total coverage of all cooomponents and their failure modes
\pause \item Provides tracable reasoning
\pause \item derived components are re-useable
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{FMMD - Failure Mode Modular De-Composition}
\textbf{Questions?}
\end{frame}
\end{document} \end{document}