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as given to Hazel to proof read

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Robin Clark 2010-10-26 15:25:06 +01:00
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fmmd_concept/fmmd_concept.tex
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@ -342,7 +342,7 @@ to smaller and smaller functional modules \cite{maikowski}.
\end{itemize} \end{itemize}
\section{Proposed Methodology \\ Failure Mode Modular De-Composition (FMMD)} \section{}
\paragraph{New methodology Must be bottom-up} \paragraph{New methodology Must be bottom-up}
In order to ensure that all component failure modes have been covered In order to ensure that all component failure modes have been covered
@ -363,7 +363,16 @@ in \cite{maikowski}. This top down technique de-composes by functionality.
Simpler and simpler functional blocks are discovered as we delve Simpler and simpler functional blocks are discovered as we delve
further into the way the system works and is built. further into the way the system works and is built.
\paragraph{Design Decision: Methodology Mus be Bottom-up}
In oder to ensure that all component failure modes are handled,
this methodology must statrt at the bottom, with base component failure modes.
In this way automated checking can be applied to all component failure modes
to ensure none have been inadvertantly excluded from the process.
\paragraph{Need for a `bottom-up' system de-composition} \paragraph{Need for a `bottom-up' system de-composition}
There is an apparent conflict here. The natural way to
de-compose a system is from the top down.
%
What is required here is to mimic this top-down de-composition What is required here is to mimic this top-down de-composition
with a bottom up technique. with a bottom up technique.
@ -381,14 +390,24 @@ This means that we have to tie base component failure modes
to SYSTEM level errors. This is the `possibility to miss failure mode effects to SYSTEM level errors. This is the `possibility to miss failure mode effects
at SYSTEM level' critism of the FTA, FMEDA and FMECA methodologies. at SYSTEM level' critism of the FTA, FMEDA and FMECA methodologies.
\paragraph{Design Decision: Methodolgy must reduce and collate errors at each functional group stage}
SYSTEMS typically have far fewer failure modes then the sum of its comonent failure modes.
Many SYSTEM level errors may be caused by a variety of component level errors.
At each fucntional group collection, there must be a process to collect
common symptoms and reduce the number of failure modes to handle.
\paragraph{How to build a SYSTEM failure behaviour model} \paragraph{How to build a SYSTEM failure behaviour model}
The next problem is how to we build a failure mode model The next problem is how to we build a failure mode model
that converges to a finite set of SYSTEM level failure modes. that converges to a finite set of SYSTEM level failure modes.
% %
It would be better would be to analyse the failure mode behaviour in each It would be better would be to analyse the failure mode behaviour of each
functional group, and determine the ways in which it, rather than its functional group, and determine the ways in which it, rather than its
components, can fail. components, can fail.
%
By doing this, the natural process whereby symptoms of the {\fg},
which can potentially be caused by more then one
component failure mode, become the target for reducing the number
of failure modes to handle as we traverse up the hierarchy.
\paragraph{Component failures and {\fg} failure symptoms} \paragraph{Component failures and {\fg} failure symptoms}