diff --git a/presentations/fmea/ad_ford_pinto_mpg_red_3_1975.jpg b/presentations/fmea/ad_ford_pinto_mpg_red_3_1975.jpg new file mode 100644 index 0000000..c684d61 Binary files /dev/null and b/presentations/fmea/ad_ford_pinto_mpg_red_3_1975.jpg differ diff --git a/presentations/fmea/burntoutpinto.png b/presentations/fmea/burntoutpinto.png new file mode 100644 index 0000000..b5d0baf Binary files /dev/null and b/presentations/fmea/burntoutpinto.png differ diff --git a/presentations/fmea/fmea_pres.tex b/presentations/fmea/fmea_pres.tex index 8d5ffe7..e67f682 100644 --- a/presentations/fmea/fmea_pres.tex +++ b/presentations/fmea/fmea_pres.tex @@ -90,6 +90,12 @@ to do this completely (all failure modes against all components). This is represented in equation~\ref{eqn:fmea_state_exp}, where $N$ is the total number of components in the system, and $cfm$ is the number of failure modes per component. +\end{frame} + + +\begin{frame} +\frametitle{Rigorous Single Failure FMEA} + \begin{equation} \label{eqn:fmea_single} @@ -125,6 +131,42 @@ double failure scenarios (for burner lock-out scenarios). \end{frame} +\section{FMEA used for Saftey Critical Aprovals} +\begin{frame} +\frametitle{Safety Critical Approvals FMEA} +Experts from Approval House and Equipement Manufacturer +discuss selected component failure modes +judged to be in critical sections of the product. + + +\begin{figure}[h] + \centering + \includegraphics[width=100pt,keepaspectratio=true]{./tech_meeting.png} + % tech_meeting.png: 350x299 pixel, 300dpi, 2.97x2.53 cm, bb=0 0 84 72 + \caption{FMEA Meeting} + \label{fig:tech_meeting} +\end{figure} +\end{frame} + +\begin{frame} +\frametitle{Safety Critical Approvals FMEA} + +\begin{figure}[h] + \centering + \includegraphics[width=70pt,keepaspectratio=true]{./tech_meeting.png} + % tech_meeting.png: 350x299 pixel, 300dpi, 2.97x2.53 cm, bb=0 0 84 72 + \caption{FMEA Meeting} + \label{fig:tech_meeting} +\end{figure} + +\begin{itemize} + \pause \item Impossible to look at all component failures let alone apply FMEA rigorously. + \pause \item In practise, failure scenarios for critical sections are contested, and either justified or extra safety measures implemented. + \pause \item Meeting notes or minutes only. +\end{itemize} + +\end{frame} + \section{PFMEA - Production FMEA : 1940's to present} \begin{frame} @@ -145,6 +187,34 @@ will return most cost benefit. \begin{frame} % benign example of PFMEA in CARS - make something up. \frametitle{PFMEA Example} + +{ +\begin{table}[ht] +\caption{FMEA Calculations} % title of Table +%\centering % used for centering table +\begin{tabular}{|| l | l | c | c | l ||} \hline + \textbf{Failure Mode} & \textbf{P} & \textbf{Cost} & \textbf{Symptom} & \textbf{RPN} \\ \hline \hline + relay 1 n/c & $1*10^{-5}$ & 38.0 & indicators fail & 0.00038 \\ \hline + relay 2 n/c & $1*10^{-5}$ & 98.0 & doorlocks fail & 0.00098 \\ \hline +% rear end crash & $14.4*10^{-6}$ & 267,700 & fatal fire & 3.855 \\ +% ruptured f.tank & & & & \\ \hline + + +\hline +\end{tabular} +\end{table} +} + +%Savings: 180 burn deaths, 180 serious burn injuries, 2,100 burned vehicles. Unit Cost: $200,000 per death, $67,000 per injury, $700 per vehicle. +%Total Benefit: 180 X ($200,000) + 180 X ($67,000) + $2,100 X ($700) = $49.5 million. +%COSTS +%Sales: 11 million cars, 1.5 million light trucks. +%Unit Cost: $11 per car, $11 per truck. +%Total Cost: 11,000,000 X ($11) + 1,500,000 X ($11) = $137 million. + + + + \end{frame} @@ -152,25 +222,134 @@ will return most cost benefit. %\subsection{Production FMEA : Example Ford Pinto : 1975} \begin{frame} \frametitle{PFMEA Example: Ford Pinto: 1975} + +\begin{figure}[h] + \centering + \includegraphics[width=200pt]{./ad_ford_pinto_mpg_red_3_1975.jpg} + % ad_ford_pinto_mpg_red_3_1975.jpg: 720x933 pixel, 96dpi, 19.05x24.69 cm, bb=0 0 540 700 + \caption{Ford Pinto Advert} + \label{fig:fordpintoad} +\end{figure} + \end{frame} + + + \begin{frame} + \frametitle{PFMEA Example: Ford Pinto: 1975} + +\begin{figure}[h] + \centering + \includegraphics[width=200pt]{./burntoutpinto.png} + % burntoutpinto.png: 376x250 pixel, 72dpi, 13.26x8.82 cm, bb=0 0 376 250 + \caption{Burnt Out Pinto} + \label{fig:burntoutpinto} +\end{figure} + + +\end{frame} + + +\begin{frame} + \frametitle{PFMEA Example: Ford Pinto: 1975} + { +\begin{table}[ht] +\caption{FMEA Calculations} % title of Table +%\centering % used for centering table +\begin{tabular}{|| l | l | c | c | l ||} \hline + \textbf{Failure Mode} & \textbf{P} & \textbf{Cost} & \textbf{Symptom} & \textbf{RPN} \\ \hline \hline + relay 1 n/c & $1*10^{-5}$ & 38.0 & indicators fail & 0.00038 \\ \hline + relay 2 n/c & $1*10^{-5}$ & 98.0 & doorlocks fail & 0.00098 \\ \hline + rear end crash & $14.4*10^{-6}$ & 267,700 & fatal fire & 3.855 \\ + ruptured f.tank & & & allow & \\ \hline + + rear end crash & $1$ & $11$ & fatal fire & 11.0 \\ + ruptured f.tank & & & fix tank & \\ \hline + +\hline +\end{tabular} +\end{table} +} + + http://www.youtube.com/watch?v=rcNeorjXMrE + +\end{frame} + \section{FMECA - Failure Modes Effects and Criticallity Analysis} +\begin{frame} +\frametitle{ FMECA - Failure Modes Effects and Criticallity Analysis} +Very similar to PFMEA, but instead of cost, a criticallity or +seriousness factor is ascribed to putative top level incidents. +FMECA has three probability factors for component failures. + +\textbf{FMECA ${\lambda}_{p}$ value.} +This is the overall failure rate of a base component. +This will typically be the failure rate per million ($10^6$) or +billion ($10^9$) hours of operation. + +\textbf{FMECA $\alpha$ value.} +The failure mode probability, usually dentoted by $\alpha$ is the probability of +is the probability of a particular failure +mode occuring within a component. +%, should it fail. +%A component with N failure modes will thus have +%have an $\alpha$ value associated with each of those modes. +%As the $\alpha$ modes are probabilities, the sum of all $\alpha$ modes for a component must equal one. +\end{frame} + +\begin{frame} +\frametitle{ FMECA - Failure Modes Effects and Criticallity Analysis} +\textbf{FMECA $\beta$ value.} +The second probability factor $\beta$, is the probability that the failure mode +will cause a given system failure. +This corresponds to `Baysian' probability, given a particular +component failure mode, the probability of a given system level failure. + +\textbf{FMECA `t' Value} +The time that a system will be operating for, or the working life time of the product is +represented by the variable $t$. +%for probability of failure on demand studies, +%this can be the number of operating cycles or demands expected. + +\textbf{Severity `s' value} +A weighting factor to indicate the seriousness of the putative system level error. +%Typical classifications are as follows:~\cite{fmd91} + +\begin{equation} + C_m = {\beta} . {\alpha} . {{\lambda}_p} . {t} . {s} +\end{equation} + +Highest $C_m$ values would be at the top of a `to~do' list +for a project manager. +\end{frame} + + \section{FMEDA - Failure Modes Effects and Diagnostic Analysis} - - -\section{FMEA - Criticism} \begin{frame} +\frametitle{ FMEDA - Failure Modes Effects and Diagnostic Analysis} +FMEDA is the methodology behind statistical (safety integrity level) +type standards (EN61508/IOC5108). +It provides a statistical overall level of safety +and allows diagnostic mitigation for self checking etc. +\end{frame} +\section{FMEA - General Criticism} +\begin{frame} +\frametitle{FMEA - General Criticism} + \begin{itemize} \pause \item Reasoning Distance - component failure to system level symptom \pause \item State explosion - impossible to perform rigorously - \pause \item - \pause \item + \pause \item Difficult to re-use previous analysis work + \pause \item FMEA type methodologies were designed for simple electro-mechanical systems of the 1940's to 1960's. \end{itemize} +FMEDA is an extension of FMEA, in that it will give higher ratings +for self checking. It + \end{frame} @@ -252,14 +431,14 @@ we must compare each failure mode against the two other components (the `$fgn-1$ For the one `zero' level FMMD case we are doing the same thing as FMEA type analysis (but on a very simple small sub-system). We are looking at how each failure~mode can effect the system/top level. -We can use equation~\ref{eqn:fmea_state_exp} to represent +We can use equation~\ref{eqn:fmea_state_exp44} to represent the number of checks to rigorously perform FMEA, where $N$ is the total number of components in the system, and $cfm$ is the number of failures per component. Where $N=3$ and $cfm=3$ we can see that the number of checks for this simple functional -group is the same for equation~\ref{eqn:fmea_state_exp} +group is the same for equation~\ref{eqn:fmea_state_exp22} and equation~\ref{eqn:anscen}. \clearpage @@ -272,7 +451,7 @@ will require 81 base level components. $$ %\begin{equation} - \label{eqn:fmea_state_exp} + \label{eqn:fmea_state_exp22} 81.(81-1).3 = 19440 % \\ %(N^2 - N).cfm %\end{equation} diff --git a/presentations/fmea/tech_meeting.png b/presentations/fmea/tech_meeting.png new file mode 100644 index 0000000..c25606b Binary files /dev/null and b/presentations/fmea/tech_meeting.png differ