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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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66
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,
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
%
@ -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].
%
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
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.
%,
%or the failure modes of the {\dc}.
%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
\fmmdglossSYMPTOM
%Or in other words
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
with its own set of failure modes.
%
\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.
%
@ -125,7 +122,7 @@ thus avoiding state explosion).
%% GARK BEGIN
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}.
%
\begin{figure}[h+]
@ -201,7 +198,7 @@ a failure in
the potential~dividers' operation.
%
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).
%
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 functional group used to derive it.
% %piss can consider this an an orthogonal WHAT???? Group ???? Collection ????
With this {\dc} model for a generic potential divider, it can be used
as a building block for other {\fgs} in the same way the base components $R1$ and $R2$ were.
This {\dc} model for a generic potential divider can be used
as a building block for other {\fgs} in the same way that the base components $R1$ and $R2$ were.
%
%\clearpage
%
@ -411,7 +408,7 @@ These op-amp failure modes are represented on the DAG in figure~\ref{fig:op1dag}
%\clearpage
%\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
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,
%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
%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}.
%Each of these failure modes will be given a {\fc} for analysis,
%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}.
% 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
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
down to the base component failure modes, %leaves of the tree (the leaves being {\bc} failure modes),
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
is extremely useful;
@ -669,7 +666,7 @@ A component is anything used to build a %a product or
system.
It could be something quite complicated
like an %integrated
micro-controller/servo motor, or quite simple like the resistor.
micro-controller/servo motor, or quite simple like a resistor.
%
A
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???
\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.
%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.
@ -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.
%
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.
%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 breaks it down.
\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}.
%
\fmmdglossFG
@ -823,16 +820,18 @@ failure rates)~\cite{mil1991,en298,fmd91}.
For instance, a simple resistor is generally considered
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
supply detailed information on the component as supplied by the manufacturer.
Electrical components have data-sheets associated with them.
%
Data sheets, supplied by the manufacturer,
are a detailed source of information on the component.
%
\fmodegloss
%
Because they are written for system designers, and to an extent advertise the product,
they rarely give %show %clearly detail the
failure modes of the component.
they rarely list %show %clearly detail the
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.
%
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
%
When modularising failure mode behaviour from the bottom up,
it is more meaningful to call them `{\dcs}'.
%
This is because they have been derived from the bottom-up according to functional
it is more meaningful to call them `{\dcs}' (i.e. they have been derived from the bottom-up according to functional
criteria, rather than with the top down approach, de-composed from
a system into 'sub-systems'.
a system into 'sub-systems').
%
\fmodegloss
\fmmdglossDC
@ -907,7 +904,7 @@ of the component.
The FMEA analyst is not usually concerned with how the component has failed
internally.
%
What the analyst need to know are the symptoms of failure.
What the analyst needs to know are the symptoms of failure.
%
\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.
%
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.
%
\fmmdglossFTA
@ -1065,7 +1062,7 @@ in a {\fg} higher in the hierarchy.
The {\em PD} derived component is now placed into a {\fg}
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
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.}.
@ -1182,7 +1179,7 @@ Ensuring this condition is described in section~\ref{sec:completetest}.
\paragraph{Mutual exclusivity of {\dc} 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.
%
@ -1209,8 +1206,7 @@ has to be made for each component {\fm} in the system.
\paragraph{State explosion problem of FMEA solved by FMMD.}
%
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
mode could be considered in the context of all other components in the system---disappears.
the traditional state explosion problem in FMEA--which lead to the ideal of XFMEA---disappears.
%
With FMMD, because the {\fgs} have small numbers of components in them, XFMEA can be easily applied within the {\fgs}.
%