Evening edit...
This commit is contained in:
parent
3d1bb83b25
commit
64165962c6
@ -338,7 +338,7 @@ fm : \mathcal{FG} \rightarrow \mathcal{F}
|
||||
|
||||
|
||||
\section{Unitary State Component Failure Mode sets}
|
||||
|
||||
\label{sec:unitarystate}
|
||||
\paragraph{Design Descision/Constraint}
|
||||
An important factor in defining a set of failure modes is that they
|
||||
should represent the failure modes as simply and minimally as possible.
|
||||
|
@ -1215,7 +1215,7 @@ for a single base~component failure mode minimal cut set~\cite{nucfta}.
|
||||
|
||||
|
||||
\subsection{Aims of FMMD Methodology}
|
||||
|
||||
\label{sec:aims}
|
||||
Taking the four current failure mode methodologies into consideration, and comparing them to the proposed FMMD methodology, the following wish list or aims can be stated.
|
||||
|
||||
\begin{itemize}
|
||||
|
@ -6,8 +6,8 @@
|
||||
The algorithm for {\em symptom extraction} is described in
|
||||
this section
|
||||
%describes the symptom abstraction process
|
||||
using set theory.
|
||||
|
||||
using set theory and procedural descriptions.
|
||||
%
|
||||
The {\em symptom abstraction process} (given the symbol `$\bowtie$') takes a functional group $FG$
|
||||
and converts it to a derived~component/sub-system $DC$.
|
||||
%The sub-system $SS$ is a collection
|
||||
@ -15,7 +15,8 @@ and converts it to a derived~component/sub-system $DC$.
|
||||
Note that
|
||||
$DC$ is a derived component at a higher level of fault analysis abstraction
|
||||
than the functional~group from which it was derived.
|
||||
Thus, it can be treated
|
||||
%Thus,
|
||||
$DC$ can be treated
|
||||
as a component with a known set of failure modes.
|
||||
|
||||
|
||||
@ -55,7 +56,7 @@ naturally formed with the abstraction levels increasing with each tier.
|
||||
|
||||
The algorithm, represented by the symbol `$\bowtie$', has been broken down into five consecutive stages.
|
||||
%These are described using the Algorithm environment in the next section \ref{algorithms}.
|
||||
By defining the process and describing it using set theory, constraints and
|
||||
By defining the process and describing it using set theory. Constraints and
|
||||
verification checks in the process are stated formally.
|
||||
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
||||
|
||||
@ -82,7 +83,7 @@ $$ \bowtie: \mathcal{FG} \rightarrow \mathcal{DC} $$
|
||||
\end{algorithmic}
|
||||
\end{algorithm}
|
||||
|
||||
The symptom abstraction methodology allows us to take a functional group of components,
|
||||
The symptom abstraction process allows us to take a functional group of components,
|
||||
analyse the failure
|
||||
mode behaviour and create a new entity, a derived~component, that has its own set of failure modes.
|
||||
The checks and constraints applied in the algorithm ensure that all component failure
|
||||
@ -179,7 +180,7 @@ given by
|
||||
|
||||
$$ dtc(F) = TC $$
|
||||
|
||||
The function \textbf{chosen} means that the failure modes for a particular test case have been chosen by
|
||||
In algorithm \ref{alg2}, the function \textbf{chosen} means that the failure modes for a particular test case have been chosen by
|
||||
a human operator and are additional to those chosen by the automated process (i.e they are special case test cases involving multiple failure modes)
|
||||
The function \textbf{unitarystate} means that all test cases can have no pairs of failure modes sourced from the component.
|
||||
\ifthenelse {\boolean{paper}}
|
||||
@ -187,7 +188,7 @@ The function \textbf{unitarystate} means that all test cases can have no pairs o
|
||||
%% perhaps ref a paper here XXXXX
|
||||
}
|
||||
{
|
||||
This is discussed in section \ref{unitarystate}.
|
||||
This is discussed in section \ref{sec:unitarystate}.
|
||||
}
|
||||
%%
|
||||
%% Algorithm 2
|
||||
@ -337,9 +338,11 @@ The analysis is primarily a human activity.
|
||||
Each test case is examined in detail.
|
||||
%
|
||||
%
|
||||
Ideally calculations or simulations
|
||||
Calculations or simulations
|
||||
are performed to determine how the failure modes in each test case will
|
||||
affect the functional~group.
|
||||
Ideally field and formal physical testing data should be used in addition
|
||||
where possible.
|
||||
%
|
||||
When the all the test cases have been analysed
|
||||
we will have a `result' for each `test case'.
|
||||
|
@ -3,14 +3,14 @@
|
||||
|
||||
% TO DO: separate these two:
|
||||
|
||||
\paragraph{Symptom Extraction Objective}
|
||||
\paragraph{Symptom Extraction Objective.}
|
||||
The objective of `symptom abstraction' is to analyse the functional~group and find
|
||||
how it can fail
|
||||
when specified components within it fail.
|
||||
Once we know how a functional~group can fail, we can treat it as a component or sub-system
|
||||
with its own set of failure modes.
|
||||
|
||||
\paragraph{FMEA applied to the Functional Group}
|
||||
\paragraph{FMEA applied to the Functional Group.}
|
||||
As the functional~group contains a set of components, the failure~modes
|
||||
that we have to consider are all the failure modes of its components, as
|
||||
developed in the function definition $fm : \;\mathcal{FG} \rightarrow \mathcal{F}$.
|
||||
@ -27,7 +27,7 @@ the test case conditions, for each test case.
|
||||
The goal of the process is to produce a set of failure modes from the perspective of the functional~group.
|
||||
%
|
||||
|
||||
\paragraph{Environmental Conditions or Applied States}
|
||||
\paragraph{Environmental Conditions or Applied States.}
|
||||
|
||||
Each test case must be considered for all applied/operational states and
|
||||
%in the for the case of each applied states or
|
||||
@ -52,7 +52,7 @@ examine environmentally sourced common mode failure scenarios.
|
||||
%%- change due to enviromental factors.
|
||||
%%-
|
||||
|
||||
\paragraph{Symptom Identification}
|
||||
\paragraph{Symptom Identification.}
|
||||
When all `test~cases' have been analysed, a second phase can be actioned. % applied.
|
||||
%
|
||||
This looks at the results of the `test~cases' as failure modes from the perspective not of the components, but of the {\fg}/sub-system.
|
||||
@ -66,7 +66,7 @@ will both cause the same failure; $no\_sound$ !
|
||||
|
||||
|
||||
|
||||
\paragraph{Collection of Symptoms}
|
||||
\paragraph{Collection of Symptoms.}
|
||||
Looking at the functional group perspective failure modes, we can collect
|
||||
some of these into common `symptoms'. Some test cases may cause
|
||||
unique failure modes at the functional group level. These can be termed
|
||||
@ -104,7 +104,7 @@ form `test cases'.
|
||||
% \item Where si,ultaneous failures are examined use overlapping contours
|
||||
% \item For each region on the diagram, make a test case
|
||||
\item Using the `test cases' as scenarios to examine the effects of component failures
|
||||
we determine failure~mode behaviour of the functional group.
|
||||
we determine the failure~mode behaviour of the functional group.
|
||||
This is a human process involving detailed analysis of the failure modes in the test case on the operation of the {\fg}.
|
||||
Where spcific environment conditions, or applied states are germane to the {\fg}, these must be examined
|
||||
for each test case.
|
||||
@ -260,8 +260,8 @@ We can thus apply the function $fm$ on this newly derived component thus:
|
||||
$$ fm(DC) = \{ SP1, SP2, SP3 \} $$
|
||||
|
||||
Note that $g_6$ has \textbf{not disappeared from the analysis process}.
|
||||
Were the designer to have overlooked this test case, it would appear as a failure mode of the derived component.
|
||||
i.e. were it not to have been grouped in $SP3$, $ fm(DC)$ would have been $ \{ SP1, SP2, g_6 \}$.
|
||||
Were the designer to have overlooked this test case, it could appear as a failure mode of the derived component.
|
||||
i.e. were it not to have been grouped in $SP3$, $ fm(DC)$ could have been $ \{ SP1, SP2, g_6 \}$.
|
||||
Because the process can be computerised, we can easily flag symptoms that have not been
|
||||
included as failure modes in a {\dc}.
|
||||
% Aw boring ! no jokes ?
|
||||
@ -275,7 +275,7 @@ from base level components cannot be overlooked.
|
||||
{
|
||||
An advantage of a bottom-up process is that failure modes
|
||||
from base level components cannot be overlooked.
|
||||
The process must not allow failure modes to be ignored or forgotten (see project aims in section \ref{requirements}).
|
||||
The process must not allow failure modes to be ignored or forgotten (see project aims in section \ref{sec:aims}).
|
||||
}
|
||||
%
|
||||
This sub-system or {\dc} $DC$, with its three error modes, can now be treated as a component
|
||||
|
@ -20,8 +20,8 @@ However, FMMD also provides the mathematical framework
|
||||
to assist in the production of the three traditional methods of static analysis.
|
||||
From the model created by the FMMD methodology, statistical, FTA and FMEA models
|
||||
can be derived.
|
||||
FMMD can model electrical, mechanical and software using a common notation,
|
||||
and can thus model an entire electro-mechanical software controlled system.
|
||||
FMMD can model electrical, mechanical and software failures using a common notation,
|
||||
and can thus model an integrated electro-mechanical software controlled system.
|
||||
|
||||
\subsection{Top Down or Natural Trouble Shooting}
|
||||
It is interesting here to look at the `natural' trouble shooting process.
|
||||
@ -95,7 +95,7 @@ that could cause a particular mode of equipment failure.
|
||||
This means that at the design stage of a product all component failure
|
||||
modes must be considered. The aim here is for complete failure mode coverage.
|
||||
This also means that we can obtain statistical estimates based on the known reliabilities
|
||||
of the components.
|
||||
of components\cite{mil1992}.
|
||||
%It also means that every component failure mode must at the very least be considered.
|
||||
|
||||
|
||||
@ -125,7 +125,7 @@ CD-player, tuner, amplifier~separate, loudspeakers and ipod~interface.
|
||||
%Thinking like this is a top~down analysis approach
|
||||
%and is the way in which FTA\cite{nucfta} analyses a System
|
||||
%and breaks it down.
|
||||
\paragraph{Sub-systems, {\fgs} and components}
|
||||
\paragraph{Sub-systems, {\fgs} and components.}
|
||||
A sub-system will be composed of components, which
|
||||
may themselves be sub-systems. However each `component'
|
||||
will have a fault/failure behaviour and it should
|
||||
@ -135,8 +135,7 @@ for each `component'.
|
||||
|
||||
If we look at the sound system example,
|
||||
the CD~player could fail in several distinct ways,
|
||||
and this could be due to a large number of
|
||||
component failure modes.
|
||||
and this could have been caused by a number of component failure modes.
|
||||
%no matter what has happened to it or has gone wrong inside it.
|
||||
|
||||
|
||||
@ -152,7 +151,7 @@ These are termed `functional~groups'. For instance the circuitry that powers th
|
||||
to illuminate the CD might contain a handful of components, and as such would make a good candidate
|
||||
to be one of the base level functional~groups.
|
||||
|
||||
\paragraph{Functional group to {\dc} process outline}
|
||||
\paragraph{Functional group to {\dc} process outline.}
|
||||
In choosing the lowest level (base component) sub-systems we would look
|
||||
for the smallest `functional~groups' of components within a system.
|
||||
We can define a functional~group as a set of components that interact
|
||||
@ -162,7 +161,7 @@ When we have analysed the fault behaviour of a functional group, we can treat it
|
||||
The fault behaviour will consist of a set of `symptoms' caused by combinations
|
||||
of its component failure modes.
|
||||
We can thus make a new `component' derived from the functional~group.
|
||||
The symptoms are the failure modes of this new `derived component'.
|
||||
The symptoms of the {\fg} are the failure modes of this new `derived component'.
|
||||
|
||||
%We can now call our functional~group a sub-system or a derived~component.
|
||||
%The goal here is to know how it will behave under fault conditions !
|
||||
|
Loading…
Reference in New Issue
Block a user