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F ailure M ode E ffect & C riticality A nalyses FMECA.

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Presentation on theme: "F ailure M ode E ffect & C riticality A nalyses FMECA."— Presentation transcript:

1 F ailure M ode E ffect & C riticality A nalyses FMECA

2 Item Function Failure Mode Cause Failure Mode Ratio α Failure Rate λ Failure Effect Severity Symptoms Criticality Risk Priority Number Immediate Level Next Level System …….. Sub System …….. Assembly …….. FMECA

3 2 1 5 4 7 13 3 8 6 12 11 10 9 1 Basket 2 Tank 3 Belt Drive 4 Motor 5 Counter Weight 6 Control Unit 7 Bearing 8 Switch & Distributor 9 Pump 10 Hot Water in 11 Cold Water in 12 Water out 13 Thermostat

4 Item Function Failure Mode Cause Failure Mode Ratio α Failure Rate λ (10^4)Hours Failure Effect Severity S Symptoms Criticality α λ S Risk Priority Number Immediate Level Next Level TANK Contain Water  Wrap  Leak  Burst Defor mation Seal fail W.L. regulat or fail 0.3 0.6 0.1 0.08 0.1 0.05  Catastr ophic Impede shaft rotation 0.7 0.5 1.0  Wet Floor Severe Noise 0.017 0.03 0.005 0.052 Valves Control Water Flow  Leak  Seize  Seal Fail  Spring failure 0.3 0.71.0 No water flow Flood 0.7 1.0 0.21 0.7 0.91 Total Criticality 0.962 System: Automatic Washing M/cSub System : WaterAssembly: Tank

5 Item Function Failure Mode Cause Failure Mode Ratio α Failure Rate λ (10^5)Hours Failure Effect Severity S Symptoms Criticality α λ S Risk Priority Number Immediate Level Next Level Basket Holds Clothes  Wrap  Crack Defor mation Overlo ad and Solids 0.5 0.4 Impede rotation Damage clothes 0.8 1.0 Noise 0.16 0.2 0.36 Bearing Support the shaft  Seize  Misali gnment  Corro sion  Loss of lub. Oil  Heavy loads 0.3 0.7 Not proper washing Shaft damage and leakage 0.7 1.0 Noise 0.147 0.49 0.637 Total Criticality 0.997 System: Automatic Washing M/cSub System : WaterAssembly: Basket

6 EVENT TREE ANAYSIS ETA 6

7 Initiating EventPivotal Events END STATES Escape of Poisonous Gas Gas Concentration is Dangerous Gas DetectedAlarm Sounds All Personnel Evacuated P=1x10 - 4 No Accident P=4.62x10 - 4 No Accident P=3.08x10 -- 4 Accident P=4.05x10 - 5 Accident P=9x10 - 5 Accident Yes No Yes No P1=0.001 P1=0.1 P1=0.9 P1=0.95 P1=0.05 P1=0.6 P1=0.4 P1=0.1 Probability of having NO Accidents = 5.62x10 - 4 Probability of having Accidents =4.38x10 - 4

8 FAULT TREE ANAYSIS FTA 8

9 Given the following system of crude oil supply. The system is composed of three pumps sharing the load and a buffer tank Construct FAILURE TREE and evaluate the probability of failure. If the Mechanical failure probability of one of the pumps is 0.3 in a period of 6 moths. Electrical Failures have a constant failure rate of 0.2 failures/month. Failure rate of the buffer tank amounts to 0.3 failures/month. Evaluate the system Failure rate in failures/month. Pump A Pump C Pump B Buffer Tank

10 System Fails OR Buffer Tank fails AND Pump A fails Pump B fails Pump C fails OR MechElect 0.3 0.05 0.2 0.25 0.015625 0.315625

11 A Computer System Failure Computer System Fails OROR Auxiliary Storage OROR OROR OROR CD CD Player Scanner UBS RAM Main Storage Peripherals Main Input Auxiliary Input ANDAND Mouse Key Board ANDAND Monitor Printer HD Mother Board

12 Method of Obtaining Cut Sets MOCUS Top Event OROR OROR OROR OROR 9 G1 G2 5 1 ANDAND G3 G4 G5 OROR 6 7 8 G6 3 OROR 4 2 1 G1 2 1 G2 G3 2 1 G4,G5 G3 2 1 5G5 6G5 3 4 9 2 1 G4,G5 3 G6 2 1 5 7 5 8 6 7 6 8 3 4 9 2

13 1 5 7 5 8 6 7 6 8 3 4 9 2 Given the Cut Sets in the previous example. Construct The Corresponding RBD 87 65 13429


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