SafetyandReliabilityAnalysisLecture2Yiliu LiuDepartment of Production and Quality EngineeringNorwegian Universityof ScienceandTechnologyyiliu.liu@ntnu.noNTNU- TrondheimNorwegian University ofScience and Technologywww.ntnu.edu
1 Safety and Reliability Analysis Lecture 2 Yiliu Liu Department of Production and Quality Engineering Norwegian University of Science and Technology yiliu.liu@ntnu.no
FAILUREANALYSISNTNU-TrondheimNorwegian University ofScience and Technologywww.ntnu.edu
2 FAILURE ANALYSIS
3Failures relatedErrorisadiscrepancybetweenacomputed,observedormeasuredvalueorconditionFailureistheeventwhenareguiredfunctionisterminatedFaultishenceastateresultingfromafailureoTarget valueTErrorAcceptabledoviatiorActualperformanceFallure(event)Fault(state)TimeNTNU-Trondheim?Norwegian University ofScience and Technologywww.ntnu.edu
3 Failures related • Error is a discrepancy between a computed, observed or measured value or condition • Failure is the event when a required function is terminated • Fault is hence a state resulting from a failure
WhatisFMECAFailure modes,effects,and criticality analysis (FMEcA):A methodologyto identify andanalyze:AllpotentialfailuremodesofthevariouspartsofasystemTheeffectsthesefailuresmayhaveonthesystemHowto avoid thefailures,and/ormitigate theeffects of thefailures on the systemFMEcA isatechnigueusedto jdentify.prioritize.andeliminatepotential failuresfrom thesystem,designorprocessbeforetheyreachthecustomer.-Omdahl(1988)FMECA is a technique to"resolve potential problems ina system before theyoccur"Initially,theFMECAWascalledFMEA(Failuremodesandeffectsanalysis).TheCinFMECAindicatesthat the criticality(or severity)ofthe variousfailure effects are considered andranked.NTNU-TrondheimNorwegian University ofScience and Technologywww.ntnu.edu
4 What is FMECA Failure modes, effects, and criticality analysis (FMECA): A methodology to identify and analyze: • All potential failure modes of the various parts of a system • The effects these failures may have on the system • How to avoid the failures, and/or mitigate the effects of the failures on the system FMECA is a technique used to identify, prioritize, and eliminate potential failures from the system, design or process before they reach the customer. – Omdahl (1988) FMECA is a technique to “resolve potential problems in a system before they occur.” Initially, the FMECA was called FMEA (Failure modes and effects analysis). The C in FMECA indicates that the criticality (or severity) of the various failure effects are considered and ranked
5WhatcanFMECAbeusedforAssist inselectingdesignalternativeswithhighreliabilityandhighsafetypotential duringtheearlydesignphasesEnsurethatall conceivablefailuremodesandtheireffectsonoperationalsuccessofthesystemhavebeenconsideredListpotential failures and identifythe severity oftheir effectsDevelopearlycriteriafortestplanningandrequirementsfortestequipmentProvidehistorical documentation forfuturereference to aid in analysis of field failuresandconsiderationofdesignchangesProvideabasisformaintenanceplanningProvideabasisforquantitativereliabilityandavailabilityanalysesNTNU-TrondheimNorwegian University of梦Science and Technologywww.ntnu.edu
5 What can FMECA be used for • Assist in selecting design alternatives with high reliability and high safety potential during the early design phases • Ensure that all conceivable failure modes and their effects on operational success of the system have been considered • List potential failures and identify the severity of their effects • Develop early criteria for test planning and requirements for test equipment • Provide historical documentation for future reference to aid in analysis of field failures and consideration of design changes • Provide a basis for maintenance planning • Provide a basis for quantitative reliability and availability analyses