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Robin Clark 2010-10-12 17:51:11 +01:00
parent 4ad9c0dfa2
commit 5d598082c2
2 changed files with 4 additions and 4 deletions
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component_failure_modes_definition/component_failure_modes_definition.tex
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@ -350,7 +350,7 @@ Electrical resistors can fail by going OPEN or SHORTED.
For a given resistor R we can apply the For a given resistor R we can apply the
function $fm$ to find its set of failure modes thus $ fm(R) = \{R_{SHORTED}, R_{OPEN}\} $. function $fm$ to find its set of failure modes thus $ fm(R) = \{R_{SHORTED}, R_{OPEN}\} $.
A resistor cannot fail with both conditions open and short active at the same time! The conditions A resistor cannot fail with the conditions open and short active at the same time! The conditions
OPEN and SHORT are thus mutually exclusive. OPEN and SHORT are thus mutually exclusive.
Because of this, the failure mode set $F=fm(R)$ is `unitary~state'. Because of this, the failure mode set $F=fm(R)$ is `unitary~state'.

6
fmmd_concept/fmmd_concept.tex
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@ -120,12 +120,12 @@ This is a bottom up methodology, which takes component failure modes
and traces them to the SYSTEM level failures. The components and traces them to the SYSTEM level failures. The components
have reliability data and this can be used to predict the have reliability data and this can be used to predict the
failure statistics in the design stage \cite{mil1992}. failure statistics in the design stage \cite{mil1992}.
It can do this using probability \footnote{for a given component failure mode there will be a $\Beta$ value, the It can do this using probability \footnote{for a given component failure mode there will be a $\beta$ value, the
probability that the component failure mode will cause a given SYSTEM failure}. probability that the component failure mode will cause a given SYSTEM failure}.
% %
This lacks precision, or in other words, determinability prediction accuracy \cite{fafmea}, This lacks precision, or in other words, determinability prediction accuracy \cite{fafmea},
as often the component failure mode can't be proven to cause a SYSTEM level failure, but as often the component failure mode can't be proven to cause a SYSTEM level failure, but
assigned a probability $\Beta$ fator by the design engineer. assigned a probability $\beta$ fator by the design engineer.
%Also, it can miss combinations of failure modes that will cause SYSTEM level errors. %Also, it can miss combinations of failure modes that will cause SYSTEM level errors.
% %
The results, as with FMEA are an $RPN$ number determing the significance of the SYSTEM fault. The results, as with FMEA are an $RPN$ number determing the significance of the SYSTEM fault.
@ -145,7 +145,7 @@ The results, as with FMEA are an $RPN$ number determing the significance of the
This is a process that takes all the components in a system, This is a process that takes all the components in a system,
and from the failure modes of those components and from the failure modes of those components
tnote{for a given component failure mode there will be a $\Beta$ value, the tnote{for a given component failure mode there will be a $\beta$ value, the
probability that the component failure mode will cause a given SYSTEM failure}. probability that the component failure mode will cause a given SYSTEM failure}.
calculates a risk factor for each. calculates a risk factor for each.