From e66fdd08a5ebef989024a91fb36af2c5322c1d72 Mon Sep 17 00:00:00 2001 From: Robin Clark Date: Sun, 31 Mar 2013 12:10:50 +0100 Subject: [PATCH] looking at FMEA process in more detail using UML to describe it. --- submission_thesis/CH2_FMEA/copy.tex | 91 ++++++++++++++---- submission_thesis/CH3_FMEA_criticism/Makefile | 2 +- .../CH3_FMEA_criticism/component_fm_rel.dia | Bin 0 -> 1062 bytes .../component_fm_rel_ana.dia | Bin 0 -> 1746 bytes .../component_fm_rel_ana_subj_obj.dia | Bin 0 -> 1987 bytes 5 files changed, 75 insertions(+), 18 deletions(-) create mode 100644 submission_thesis/CH3_FMEA_criticism/component_fm_rel.dia create mode 100644 submission_thesis/CH3_FMEA_criticism/component_fm_rel_ana.dia create mode 100644 submission_thesis/CH3_FMEA_criticism/component_fm_rel_ana_subj_obj.dia diff --git a/submission_thesis/CH2_FMEA/copy.tex b/submission_thesis/CH2_FMEA/copy.tex index 0c55844..af0cd9a 100644 --- a/submission_thesis/CH2_FMEA/copy.tex +++ b/submission_thesis/CH2_FMEA/copy.tex @@ -14,13 +14,27 @@ on the behaviour and safety of the system.'' This chapter introduces Failure Mode Effect Analysis (FMEA). %It begins with a simple example to demonstrate the basic concept of FMEA %and then -It starts by looking at how we determine the failure modes associated with components. +It starts with a generic conceptual overview of the process. +It then looks at the stages of the FMEA process in greater detail, starting with +how we determine the failure modes associated with components. Two common electrical components, the resistor and the operational amplifier and examined in the context of two sources of information that define failure modes. -A simple example of an FMEA is then given. -The four main variants are then described and finally we conclude by describing concepts +% +A simple example of an FMEA is then given, using a hypothetical {\ft} milli-amp reader. +% +The four main variants are then described and we then develop %conclude by describing concepts +the concepts that underlie the usage and philosophy of FMEA. - +% +We then return to the overall process of FMEA +and model it using UML. +% +By using UML we define relationships between the data objects +described at the start of this chapter. +% +The act +of defining relationships between the data objects +in FMEA raise questions about the nature of this process. @@ -68,11 +82,49 @@ demonstrate a single FMEA analysis stage, describes the four main variants of F and explores some concepts with which we can discuss and evaluate the effectiveness of FMEA. +\section{FMEA Process} + +We begin FMEA with the basic, or starting components. +This components are the sort we buy in or consider as pre-assembled modules. +We need to know how these can fail. So our first relationship +is between a {\bc} and its failure modes, see figure~\ref{fig:component_fm_rel}. + +%DIAGRAM of Base components and failure modes + +\begin{figure}[h] + \centering + \includegraphics[width=400pt]{./CH3_FMEA_criticism/component_fm_rel.png} + % component_fm_rel.png: 368x71 pixel, 72dpi, 12.98x2.50 cm, bb=0 0 368 71 + \caption{Base Component to Failure Modes relationship} + \label{fig:component_fm_rel} +\end{figure} + +The next stage is reasoning. We take a component failure +mode and analyse its effect on some of the other components in the system. +The result of this is a system level failure, or symptom. +The analysis would typically be one line in a spreadsheet entry. +and analysis to symptom relationship is generally % considered +one-to-one, however here (see figure~\ref{fig:component_fm_rel_ana}), we allow for the possibility +of more than one failure symptom. +%DIAGRAM of reasoning and Symptoms. + +\begin{figure}[h] + \centering + \includegraphics[width=400pt]{./CH3_FMEA_criticism/component_fm_rel_ana.png} + % component_fm_rel_ana.png: 369x184 pixel, 72dpi, 13.02x6.49 cm, bb=0 0 369 184 + \caption{FMEA analyis entry data relationships} + \label{fig:component_fm_rel_ana} +\end{figure} + +Figure ~\ref{fig:component_fm_rel_ana} defines the data relationships +for FMEA. This model is expanded upon in the conclusion +of this chapter. \section{Determining the failure modes of components} \label{sec:determine_fms} In order to apply any form of FMEA we need to know the ways in which -the components we are using can fail. +the components we are using can fail. In practise, this part of the process is guided by +the standards to which we are seeking to conform to. % \footnote{A good introduction to hardware and software failure modes may be found in~\cite{sccs}[pp.114-124].} % @@ -1147,14 +1199,8 @@ It has a simple final result, a Safety Integrity Level (SIL) from 1 to 4 (wher %FMEA can be used as a term simple to mean Failure Mode Effects Analysis, and is %part of product approval for many regulated products in the EU and the USA... - - - - - \section{FMEA used for Safety Critical Approvals} - \subsection{DESIGN FMEA: Safety Critical Approvals FMEA} \begin{figure}[h] \centering @@ -1164,7 +1210,7 @@ It has a simple final result, a Safety Integrity Level (SIL) from 1 to 4 (wher \label{fig:tech_meeting} \end{figure} %Static FMEA, Design FMEA, Approvals FMEA - +% Experts from Approval House and Equipment Manufacturer discuss selected component failure modes judged to be in critical sections of the product. @@ -1172,11 +1218,6 @@ judged to be in critical sections of the product. This could be considered as a design check method, deliberately looking for weaknesses at a theoretical level. - - - - - \subsection{DESIGN FMEA: Safety Critical Approvals FMEA} % \begin{figure}[h] @@ -1194,6 +1235,22 @@ looking for weaknesses at a theoretical level. \end{itemize} +\section{Conclusion} + +Returning to the FMEA model, we now show that +figure holds for the five variants of FMEA discussed. +We can however, extend this +with subjective failure mode symptoms (see figure~\ref{fig:component_fm_rel_ana_subj_obj}). + + +\begin{figure}[h] + \centering + \includegraphics{./CH3_FMEA_criticism/component_fm_rel_ana_subj_obj.png} + % component_fm_rel_ana_subj_obj.png: 694x303 pixel, 72dpi, 24.48x10.69 cm, bb=0 0 694 303 + \caption{FMEA UML data representation with subjective system level failure modes.} + \label{fig:component_fm_rel_ana_subj_obj} +\end{figure} + % MOVED TO CH3: 15MAR2013 % diff --git a/submission_thesis/CH3_FMEA_criticism/Makefile b/submission_thesis/CH3_FMEA_criticism/Makefile index cdaf773..76b99c3 100644 --- a/submission_thesis/CH3_FMEA_criticism/Makefile +++ b/submission_thesis/CH3_FMEA_criticism/Makefile @@ -3,7 +3,7 @@ # # Place all .dia files here as .png targets # -DIA = distcon.png +DIA = distcon.png component_fm_rel.png component_fm_rel_ana.png component_fm_rel_ana_subj_obj.png doc: $(DIA) diff --git a/submission_thesis/CH3_FMEA_criticism/component_fm_rel.dia b/submission_thesis/CH3_FMEA_criticism/component_fm_rel.dia new file mode 100644 index 0000000000000000000000000000000000000000..781fdcabf2440f105b0ab90890780177c2975c9d GIT binary patch literal 1062 zcmV+>1lju^iwFP!000021MOMcuHrTnedjBpoVTjuB+i9o7#MXbReh*551l?ElbGO+ zVQe-Nd}P(g-1 z8)@2cf(S{JJu9CgDFs<k{L+mwjd7Ca zOzt&`@j_tqy*st3t{}K4^%{$M+GNdBqC(_;-3aN(ll?!6DWg&q#Nye@FV0IbrSd_Q zt8Jp4ATmKBCaj60dP9pwK;T0NRWsbc56rPMwhleH9d7ZqaP)2A#M{D=biU?73PfZR za=|&ph!v<(Z1DX!X^5zz*txQLRIwyd@(c4{BAQ-PK=Js$-FEBFjRlF$Z`_lJjx0M8 z$<_RIpmr76_XB0$l9VhcZks(}@?q)sk4ax&om{=E;XT<0qNf^nbhD@@{*>`re3 zJ2<|4?>?|}#dq_T)8b_-Y~Qv<#nCHB`whR!Bi33aYpvd_^??P|5<5e3w#2Z3W4aS) z0pH0X6}RA>D=)KlToCG7OxLpJC)<;_+9CMYEHA@McASOJ7)aM?gfrQOm_65)C?RyO zCWct5YpL94N~ct+82US=TP#V4js^Ml88kLc%f>N*Z=POGKhRSqUdhILfKE;I%$t{K z_5)H!)|e%@eKj%LBxNVBL}|6m+cw5FpHh8mR8z4ZD@*NO3j3-O48S-u9t#BCfWo9; 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