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FMEA and FMECA - Failure Mode, Effects, and Criticality Analysis |
Failure Mode, Effects and Criticality Analysis
| The FMEA is a reliability modeling method, based on an qualitative approach, whilst the FMECA (Extension of FMEA) takes a quantitative approach and assigns a criticality and probability of occurrence for each given failure mode. FMECA is a procedure, which should be implemented during the design phase to identify potential design weaknesses (failure modes) in a system and classify them according to their severity and probability of consequences.
The main objective of the FMECA is to improve design thus eliminating as many system failures and hazards as possible, to increase the probability of a fail-safe operating, and to reduce the risk and failure rate of consequential damage. The FMECA is a bottom to top analysis in which the designer assigns for each part a list of failure modes and the effects of those failure modes on the system behavior.
FMEA/FMECA requires the following steps in the design process :
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Defining system block diagram and functional interrelationships
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Identifying all potential failure modes in the system including effects of the failure mode from the basic function of the system up to the upper system function
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Analyzing the system failure modes and their potential severity category
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Defining all failure detection methods, including failure rates
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Identifying and recommend redesign action to reduce the risk of critical failures
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Identifying the problems that couldn't be reduced by the design and recommend the necessary action to control the failure risk.
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