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Slide 2 Failure Mode and Effects Analysis (FMEA) 9/28/2013Ohio University - Dr. Cyders1 FMEA is a design tool for assessing risk associated with the different ways (modes) in which a part or system can fail, identifies the effects of those failures, and provides a structure for revising the design to mitigate risk where necessary. Inductive process, asks question If this failure occurred, then what could happen? Provides a method for quantitative analysis of risk Useful for comparing design concepts and refining designs Documents safety review in an easy-to-read format Slide 3 9/28/2013Ohio University - Dr. Cyders2 Process Steps: 1: Identify modes of failure (e.g.: car wont stop) 2: Identify consequences & related systems for each mode 3: Rate the Severity (S) of each effect 4: Identify potential root causes for each failure mode 5: Rate the Probability of Occurrence (O) of each root cause 6: Identify process controls and indicators (e.g.: brake squeal) 7: Rate Detectability (D) of each mode/root cause 8: Calculate risk priority (S*O*D) and criticality (S*O) 9: Use design to mitigate high-risk or highly critical failures, and re-assess to ensure goals have been achieved Slide 4 9/28/2013Ohio University - Dr. Cyders3 Example: Battery Headlight Switch Possible Failure Modes: Light doesnt turn on Light doesnt turn off Possible Consequences: Light doesnt turn on Driver cant see obstacles Car inoperable at night (8) Light doesnt turn off Battery dies Car wont start (10) Possible Root Causes: Light doesnt turn on Battery dead (8) Broken wire (3) Headlight out (10) Switch corroded (2) Switch broken (3) Slide 5 9/28/2013Ohio University - Dr. Cyders4 Example: Battery Headlight Switch Possible Failure Modes: Light doesnt turn on Light doesnt turn off Possible Consequences: Light doesnt turn on Driver cant see obstacles Car inoperable at night (8) Light doesnt turn off Battery dies Car wont start (10) Possible Root Causes: Light doesnt turn off Short circuit in switch (2) Operator error (left on) (8) Slide 6 9/28/2013Ohio University - Dr. Cyders5 Example: Battery Headlight Switch Controls/indicators: Light doesnt turn on User notices lights on in dark Light doesnt turn off User notices lights on in dark Detectability: Light doesnt turn on (6) User notices lights on in dark User doesnt notice lights not on during day Light doesnt turn off (6) User notices lights on in dark User doesnt notice lights not on during day Slide 7 9/28/2013Ohio University - Dr. Cyders6 Example: Possible EffectRoot CauseSODRPNCrit. Car inoperable at night Battery dead 108648080 Broken wire8314424 Headlight out 81048080 Switch corroded 829616 Switch broken 8314424 Failure Mode: Light doesnt turn on Slide 8 9/28/2013Ohio University - Dr. Cyders7 Example: Possible EffectRoot CauseSODRPNCrit. Car inoperable at night Battery dead 108216080 Broken wire836030 Headlight out 61012060 Switch corroded 824020 Switch broken 836030 Failure Mode: Light doesnt turn on Redesign: Use two headlights instead of one, add visual lights- on display in console. Slide 9 9/28/2013Ohio University - Dr. Cyders8 Example: Possible EffectRoot CauseSODRPNCrit. Car wont startShort circuit in switch 102714020 Operator error 856080 Failure Mode: Light doesnt turn off Slide 10 9/28/2013Ohio University - Dr. Cyders9 Example: Possible EffectRoot CauseSODRPNCrit. Car wont startShort circuit in switch 10224020 Operator error 816080 Failure Mode: Light doesnt turn off Redesign: Add audible indicator when drivers door is opened while lights are on, add visual lights-on display in console.