39 lines
2.1 KiB
TeX
39 lines
2.1 KiB
TeX
{
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\section{Introduction}
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This chapter describes a process for taking a {\fg} of components,
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applying FMEA analysis on all the component failure modes possible in that {\fg},
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and then determining how that {\fg} can fail.
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%
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%
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With this information, we can treat the {\fg}
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as a component in its own right.
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This new component, is derived from the {\fg}.
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In the field of safety engineering this derived component corresponds to a low~level sub-system.
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%The technique uses a graphical notation, based on Euler\cite{eulerviz} and Constraint diagrams\cite{constraint} to model failure modes and failure mode common symptom collection. The technique is designed for making building blocks for a hierarchical fault model.
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%
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Once the failure modes have been determined for a sub-system/{\dc},
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this {\dc} can be combined with others to form {\fgs} groups
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to model
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higher level sub-systems/{\dcs}.
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%
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In this way a hierarchy to represent the fault behaviour
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of a system can be built from the bottom~up. This process can continue
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until there is a complete hierarchy representing the failure mode
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behaviour of the entire system under analysis.
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%FMMD hierarchy
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Using the FMMD technique the hierarchy is built from the bottom up to
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ensure complete failure mode coverage.
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Because the process is bottom-up, syntax checking and tracking can ensure that
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no component failure mode can be overlooked.
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Once a hierarchy is in place, it can be converted into a fault data model.
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%
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From the fault data model, automatic generation
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of FTA \cite{nasafta} (Fault Tree Analysis) and mimimal cuts sets \cite{nucfta} are possible.
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Also statistical reliability/probability of failure~on~demand \cite{en61508} and MTTF (Mean Time to Failure) calculations can be produced
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automatically \footnote{Where component failure mode statistics are available \cite{mil1991}}.
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%
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This chapter focuses on the process of converting {\fgs} to {\dcs}, or building the `blocks' of the FMMD hierarchy.
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We can term this stage in FMMD analysis as the `symptom extraction' process.
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The symptom extraction or abstraction process, is the key process in creating an FMMD hierarchy.
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}
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