.

fmmd_concept/fmmd_concept.tex

@@ -9,7 +9,7 @@ creating failure mode models of safety critical systems, which
 has a common and integrateable notation
 for mechanical, electronic and software domains.
 In addition, the methodology address the traditional weaknesses of
-Fault Tree Analysis (FTA), Fault Mode Effects Analysis (FMEA) 
+Fault Tree Analysis (FTA), Fault Mode Effects Analysis (FMEA), Faliue Mode Effects Criticallity Analysis (FMECA)
 and Failure Mode Effects and Diagnostic Analysis (FMEDA).
 The proposed methodology is bottom-up and 
 modular.}
@@ -39,12 +39,15 @@ of analysis.
 The FMMD
 methodology presented here provides a more detailed and analytical
 modelling system which will create a more complete and detail hierarchical failure mode model from which
-the data models from FTA, FMEA and the statistical approach can be 
+the data models from FTA, FMEA, FMECA and FMEDA (the statistical approach) can be 
 derived if required.
 It also applies rigorous checking in the analysis stages
 ensuring that all component failure modes must be considered in the model.
 
-FMMD
+%
+This methodology has been named Failure Mode Modular De-composition (FMMD)
+because it de-composes a SYSTEM into a hierarchy of modules or {\dc}s.
+This
 \ifthenelse {\boolean{paper}}
 {
 paper
@@ -52,15 +55,17 @@ paper
 {
 chapter
 }
-presents a bottom up modular methodology, a extension and refinement to the FMEA, where instead of looking
-at individual component failure modes and deciding on their impact on the SYSTEM 
-it uses the component failure modes, to build modules or derived components,
-using incremental steps to build a hierarchical model.
+presents the design considerations that determined
+the FMMD methodology.
+FMMD is an incremental bottom up FMEA process. 
+It first beiefly reviews the four traditional
+static failure mode analysis methodologies and 
+lists their known weaknesses. A wish list is then drawn up
+addressing these weaknesses and adding some extra requirements.
+Using this wish list the phiosophy for the new methodology
+is built up.
 %
-This methodology has been named Failure Mode Modular De-composition (FMMD)
-because it de-composes a SYSTEM into a hierarchy of modules or {\dc}s.
-%
-It does this by working from the bottom up, taking small groups
+FMMD works by working from the bottom up, taking small groups
 of components, {\fgs}, and then analysing how they can fail.
 This analysis is performed using FMEA from a micro rather than a macro perspective.
 Thus instead of looking at a component failure modes, and determining how
@@ -273,6 +278,25 @@ In order to ensure that all component failure modes have been covered
 the methodology will have to work from the bottom-up
 and start with the component failure modes.
 %
+\paragraph{Natural Fault Finding is top down}
+The traditional fault finding, or natual fault finding
+is to work form the top down. On encountering a 
+fault the symptom is first klnow at the top or
+SYSTEM level. By de-composing the functionality of the faulty system and testing
+we can further de-compose the system until we find the
+faulty base level component.
+De-composition of electrical circuits is formalised and explored
+in \cite{maikowski}. This top down technique de-composes by functionality.
+Simpler and simpler functional blocks are discovered as we delve
+further into the way the system works and is built.
+
+What is required here is to mimic this top-down de-composition
+with a bottom up technique.
+
+By taking components that form {\fg}s form the nottom up
+and then taking those to form higher level
+{\fg}s we can mimic the analysis process from the bottom up.
+
 \paragraph{How to build a SYSTEM failure behaviour model}
 The next problem is how to we build a failure mode model
 that converges to a finite set of SYSTEM level failure modes.