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tidy up of CH4 after WE removal, CH5 and CH6 next, better check App A too

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Robin P. Clark 2013-09-12 09:10:15 +01:00
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submission_thesis/CH4_FMMD/copy.tex
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@ -26,7 +26,7 @@ FMMD is in essence a modularised variant of traditional FMEA~\cite{sccs}[pp.34-
% %
In order to analyse from the bottom-up and apply a modular methodology, In order to analyse from the bottom-up and apply a modular methodology,
small groups of components that naturally small groups of components that naturally
work together to perform a simple function are chosen: these groups are termed `{\fgs}'. work together to perform simple functions are chosen: these groups are termed `{\fgs}'.
% %
\fmmdglossFG \fmmdglossFG
% %
@ -60,34 +60,31 @@ All the failure modes of all the components within a {\fg} are collected.
%A flat set is a set containing just the failure modes and not sets of failure modes~\cite{joyofsets}[p.8]. %A flat set is a set containing just the failure modes and not sets of failure modes~\cite{joyofsets}[p.8].
% %
Each component failure mode can considered as a `failure~scenario' or 'test~case' Each component failure mode can considered as a `failure~scenario' or 'test~case'
applied to a {\fg}. to be applied applied to the {\fg}.
% %
Each of these failure modes, and optionally combinations of them, are Each of these failure modes, and optionally combinations of them, are
formed into test~cases which formed into test~cases which
are analysed for their effect on the failure mode behaviour of the `{\fg}'. are analysed for their effect on the failure mode behaviour of the {\fg}.
% %
Once the failure mode behaviour of the {\fg} is obtained, its symptoms of failure can be determined. Once the failure mode behaviour of the {\fg} is obtained, its symptoms of failure can be determined.
%, %,
%or the failure modes of the {\dc}. %or the failure modes of the {\dc}.
%for the {\fg}. %for the {\fg}.
% %
These symptoms are treated as failure modes of the {\fg}. These symptoms are then treated as failure modes of the {\fg}.
% %
\fmmdglossFG \fmmdglossFG
\fmmdglossSYMPTOM \fmmdglossSYMPTOM
%Or in other words %Or in other words
That is, how the {\fg} can fail has been determined. That is, how the {\fg} can fail has been determined.
% %
As a set of failure modes has been defined for the {\fg} it can be treated as a component. As a set of failure modes has been defined for the {\fg} it can be treated as a component in its own right.
% %
The {\fg} can be considered as a `{\dc}' % sort of super component The {\fg} can be considered as a `{\dc}' % sort of super component
with its own set of failure modes. with its own set of failure modes.
% %
\fmmdglossDC \fmmdglossDC
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% UP TO HERE IN WE REMOVAL 11SEP2013
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
%This {\dc} has a set of failure modes: we can thus treat it as a `higher~level' component. %This {\dc} has a set of failure modes: we can thus treat it as a `higher~level' component.
% %
@ -125,7 +122,7 @@ thus avoiding state explosion).
%% GARK BEGIN %% GARK BEGIN
The principles of FMMD are demonstrated, by using it to analyse a The principles of FMMD are demonstrated, by using it to analyse a
commonly used circuit, a non-inverting amplifier built from an op amp~\cite{aoe}[p.234] and common circuit, the non-inverting amplifier built from an op amp~\cite{aoe}[p.234] and
two resistors; a circuit schematic for this is shown in figure \ref{fig:noninvamp}. two resistors; a circuit schematic for this is shown in figure \ref{fig:noninvamp}.
% %
\begin{figure}[h+] \begin{figure}[h+]
@ -201,7 +198,7 @@ a failure in
the potential~dividers' operation. the potential~dividers' operation.
% %
For instance For instance
if resistor $R_1$ were to become open, then the potential~divider would not be grounded and the if resistor $R_1$ were to go open, then the potential~divider would not be grounded and the
voltage output from it would float high (+ve). voltage output from it would float high (+ve).
% %
This would mean the resulting failure of the potential~divider would be voltage high output. This would mean the resulting failure of the potential~divider would be voltage high output.
@ -352,8 +349,8 @@ This {\dc} will have two failure modes, $HighPD$ and $LowPD$.
% The derived component is defined by its failure modes and % The derived component is defined by its failure modes and
% the functional group used to derive it. % the functional group used to derive it.
% %piss can consider this an an orthogonal WHAT???? Group ???? Collection ???? % %piss can consider this an an orthogonal WHAT???? Group ???? Collection ????
With this {\dc} model for a generic potential divider, it can be used This {\dc} model for a generic potential divider can be used
as a building block for other {\fgs} in the same way the base components $R1$ and $R2$ were. as a building block for other {\fgs} in the same way that the base components $R1$ and $R2$ were.
% %
%\clearpage %\clearpage
% %
@ -411,7 +408,7 @@ These op-amp failure modes are represented on the DAG in figure~\ref{fig:op1dag}
%\clearpage %\clearpage
%\paragraph{Modelling the OP amp with the potential divider.} %\paragraph{Modelling the OP amp with the potential divider.}
The op-amp and the {\dc} {\em PD} now % andrew heavily critised this sentence but it made sense to Chris and I The op-amp and the {\dc} {\em PD} now % andrew heavily critised this sentence but it made sense to Chris and I
form a {\fg} to model the failure mode behaviour of the non-inverting amplifier. formed into a {\fg} to model the failure mode behaviour of the non-inverting amplifier.
% %
%piss have the failure modes of the {\dc} for the potential divider, %piss have the failure modes of the {\dc} for the potential divider,
%so we do not need to go back and consider the individual resistor failure modes that defined its behaviour. %so we do not need to go back and consider the individual resistor failure modes that defined its behaviour.
@ -419,7 +416,7 @@ form a {\fg} to model the failure mode behaviour of the non-inverting amplifier.
%piss can now create a {\fg} for the non-inverting amplifier %piss can now create a {\fg} for the non-inverting amplifier
%by bringing together the failure modes from \textbf{opamp} and \textbf{PD}. %by bringing together the failure modes from \textbf{opamp} and \textbf{PD}.
% %
The two components in this new {\fg}, the op-amp and the {\dc} {\em PD} have failure modes, which are used The two components in this new {\fg}, the op-amp and the {\dc} {\em PD} have failure modes which are used
as {\fcs} in table~\ref{tbl:ampfmea1}. as {\fcs} in table~\ref{tbl:ampfmea1}.
%Each of these failure modes will be given a {\fc} for analysis, %Each of these failure modes will be given a {\fc} for analysis,
%and this is represented in table \ref{tbl:ampfmea1}. %and this is represented in table \ref{tbl:ampfmea1}.
@ -601,7 +598,7 @@ as {\fcs} in table~\ref{tbl:ampfmea1}.
% %
For this amplifier configuration there are three {\dc} failure modes; {\em AMP\_High, AMP\_Low, LowPass}. % see figure~\ref{fig:fgampb}. For this amplifier configuration there are three {\dc} failure modes; {\em AMP\_High, AMP\_Low, LowPass}. % see figure~\ref{fig:fgampb}.
% HTR 05SEP2012 % HTR 05SEP2012
This model now has two stages of analysis, as represented in figure~\ref{fig:eulerfmmd}. This model now has two stages of analysis. %, as represented in figure~\ref{fig:eulerfmmd}.
% %
From the analysis in table \ref{tbl:ampfmea1} the {\dc} {\em NONINVAMP} can be created, which From the analysis in table \ref{tbl:ampfmea1} the {\dc} {\em NONINVAMP} can be created, which
represents the failure mode behaviour of the non-inverting amplifier. represents the failure mode behaviour of the non-inverting amplifier.
@ -639,7 +636,7 @@ It is possible to traverse this DAG, tracing the top level % symptoms
failure modes failure modes
down to the base component failure modes, %leaves of the tree (the leaves being {\bc} failure modes), down to the base component failure modes, %leaves of the tree (the leaves being {\bc} failure modes),
and thus determine all possible causes for and thus determine all possible causes for
the three high level symptoms, i.e. the failure~modes of the non-inverting amplifier {\dc} {\em INVAMP}. the three high level symptoms, i.e. the {\bc} failure~modes of the non-inverting amplifier {\dc} {\em INVAMP}.
% %
Knowing all possible causes for a top level event/failure~mode Knowing all possible causes for a top level event/failure~mode
is extremely useful; is extremely useful;
@ -669,7 +666,7 @@ A component is anything used to build a %a product or
system. system.
It could be something quite complicated It could be something quite complicated
like an %integrated like an %integrated
micro-controller/servo motor, or quite simple like the resistor. micro-controller/servo motor, or quite simple like a resistor.
% %
A A
component is usually identified by its name, a manufacturer's part number and perhaps component is usually identified by its name, a manufacturer's part number and perhaps
@ -691,7 +688,7 @@ in the chip would be considered to be a separate {\bc}.
% CAN WE FIND SUPPORT FOR THIS IN LITERATURE??? % CAN WE FIND SUPPORT FOR THIS IN LITERATURE???
\fmmdglossBC \fmmdglossBC
% %
The above definition of a part, needs further refinement, and to be defined as % defining The above definition of a part, needs further refinement, i.e. to be defined as % defining
an atomic entity. % used as a building block. an atomic entity. % used as a building block.
%The term component, in American English, can mean a building block or a part. %The term component, in American English, can mean a building block or a part.
%In British-English a component generally is given to mean the definition for part above. %In British-English a component generally is given to mean the definition for part above.
@ -726,7 +723,7 @@ A component can be viewed as a sub-system that is a part of some larger system.
% %
A modular system common to many homes is the sound separates audio system or stereo hi-fi. A modular system common to many homes is the sound separates audio system or stereo hi-fi.
% %
This is used as an example to describe the concepts {\fg} and {\dc} found in FMMD. This is used as an example to describe the concepts of {\fg} and {\dc} used by FMMD.
% %
For instance a stereo amplifier separate/slave is a component. For instance a stereo amplifier separate/slave is a component.
%The %The
@ -739,7 +736,7 @@ CD-player, tuner, amplifier~separate, loudspeakers and ipod~interface.
%and is the way in which FTA\cite{nucfta} analyses a System %and is the way in which FTA\cite{nucfta} analyses a System
%and breaks it down. %and breaks it down.
\paragraph{Functional Groupings and Components.} % {\fgs} and components.} \paragraph{Functional Groupings and Components.} % {\fgs} and components.}
Components can be composed of components, recursively down to Components can be composed of components, recursively on down to
the {\bcs}. the {\bcs}.
% %
\fmmdglossFG \fmmdglossFG
@ -823,16 +820,18 @@ failure rates)~\cite{mil1991,en298,fmd91}.
For instance, a simple resistor is generally considered For instance, a simple resistor is generally considered
to fail in two ways, it can go open circuit or it can short. to fail in two ways, it can go open circuit or it can short.
% %
Electrical components have data-sheets associated with them. The data sheets Electrical components have data-sheets associated with them.
supply detailed information on the component as supplied by the manufacturer. %
Data sheets, supplied by the manufacturer,
are a detailed source of information on the component.
% %
\fmodegloss \fmodegloss
% %
Because they are written for system designers, and to an extent advertise the product, Because they are written for system designers, and to an extent advertise the product,
they rarely give %show %clearly detail the they rarely list %show %clearly detail the
failure modes of the component. failure modes. % of the component.
% %
For FMEA purposes, ideally failure modes along with For FMEA purposes, ideally, failure modes along with
with environmental factors and MTTF~\cite{sccs}[p.165] statistics would be presented. with environmental factors and MTTF~\cite{sccs}[p.165] statistics would be presented.
% %
Given the growing usage of FMEA/FMEDA and the emergence of SIL as a safety benchmark in industry, this may change. Given the growing usage of FMEA/FMEDA and the emergence of SIL as a safety benchmark in industry, this may change.
@ -885,11 +884,9 @@ it is common to term the modules identified as sub-systems.
\fmmdglossFG \fmmdglossFG
% %
When modularising failure mode behaviour from the bottom up, When modularising failure mode behaviour from the bottom up,
it is more meaningful to call them `{\dcs}'. it is more meaningful to call them `{\dcs}' (i.e. they have been derived from the bottom-up according to functional
%
This is because they have been derived from the bottom-up according to functional
criteria, rather than with the top down approach, de-composed from criteria, rather than with the top down approach, de-composed from
a system into 'sub-systems'. a system into 'sub-systems').
% %
\fmodegloss \fmodegloss
\fmmdglossDC \fmmdglossDC
@ -907,7 +904,7 @@ of the component.
The FMEA analyst is not usually concerned with how the component has failed The FMEA analyst is not usually concerned with how the component has failed
internally. internally.
% %
What the analyst need to know are the symptoms of failure. What the analyst needs to know are the symptoms of failure.
% %
\fmmdglossSYMPTOM \fmmdglossSYMPTOM
% %
@ -961,7 +958,7 @@ An advantage of working from the bottom up is that it can be ensured that
all component failure modes must be considered. all component failure modes must be considered.
% %
A top down approach (such as FTA) A top down approach (such as FTA)
can miss individual failure modes of components~\cite{faa}[Ch.~9], can miss~\cite{faa}[Ch.~9] individual failure modes of components,
especially where there are non-obvious top-level faults. especially where there are non-obvious top-level faults.
% %
\fmmdglossFTA \fmmdglossFTA
@ -1065,7 +1062,7 @@ in a {\fg} higher in the hierarchy.
The {\em PD} derived component is now placed into a {\fg} The {\em PD} derived component is now placed into a {\fg}
with the op-amp. with the op-amp.
% %
This {\fg} is now analysed and a {\dc} created to represent the failure mode behaviour This {\fg} is analysed and a {\dc} created to represent the failure mode behaviour
of the {\em INVAMP}\footnote{The results of this analysis are placed into the analysis~report. This will contain of the {\em INVAMP}\footnote{The results of this analysis are placed into the analysis~report. This will contain
mapping relationships between the component {\fms} and the {\dc} {\fms} and ideally, descriptions that would mapping relationships between the component {\fms} and the {\dc} {\fms} and ideally, descriptions that would
aid auditors to understand the reasoning behind each analysis test~case.}. aid auditors to understand the reasoning behind each analysis test~case.}.
@ -1182,7 +1179,7 @@ Ensuring this condition is described in section~\ref{sec:completetest}.
\paragraph{Mutual exclusivity of {\dc} failure modes.} \paragraph{Mutual exclusivity of {\dc} failure modes.}
% %
It is a desirable feature of a component that its failure modes It is a desirable feature of a component that its failure modes
are mutually exclusive. are naturally mutually exclusive.
% %
This also applies to {\dcs} produced in the FMMD process. This also applies to {\dcs} produced in the FMMD process.
% %
@ -1209,8 +1206,7 @@ has to be made for each component {\fm} in the system.
\paragraph{State explosion problem of FMEA solved by FMMD.} \paragraph{State explosion problem of FMEA solved by FMMD.}
% %
Because FMMD considers failure modes within functional groups; Because FMMD considers failure modes within functional groups;
the traditional state explosion problem in FMEA where the ideal of exhaustive FMEA (XFMEA)---where each failure the traditional state explosion problem in FMEA--which lead to the ideal of XFMEA---disappears.
mode could be considered in the context of all other components in the system---disappears.
% %
With FMMD, because the {\fgs} have small numbers of components in them, XFMEA can be easily applied within the {\fgs}. With FMMD, because the {\fgs} have small numbers of components in them, XFMEA can be easily applied within the {\fgs}.
% %