Download presentation
Presentation is loading. Please wait.
1
University of Alabama in Huntsville
Using FMEA to Address Warranty Duration Daniel Sillivant University of Alabama in Huntsville
2
RAM VIII Training Summit
Outline FMEA Process Reliability Block Diagrams Critical Items List MTBF and Reliability Calculations OC Curve for Number of Tests Warranty Decisions RAM VIII Training Summit November 3-4, 2015
3
Failure Mode and Effect Analysis ( FMEA)
FMEA: Methodology designed to identify potential failure modes Basic Procedure: Identify the item(s) to be analyzed Identify the Function(s), Failure Mechanism(s) (Cause) Failure Mode(s) (How) Failure Effect(s) (Results) Evaluate the issues identified by the analysis Additional Tools Critical Items List (CIL) Reliability Block Diagram (RBD) Reliability Calculations Warranty Confidence - OC Curves Physical Testing RAM VIII Training Summit November 3-4, 2015
4
Sources of Failure Mechanisms
Transportation Packing Handling at each stage of shipment from origin to end user Truck, Rail, Aviation & Sea Storage Distribution chain At end user Operational conditions of use (intrinsic) Result from system function Ambient conditions of use (extrinsic) Result from environmental exposure and from proximate parts functionality RAM VIII Training Summit November 3-4, 2015
5
Failure Mechanisms (Causes)
Questions: What mechanism (Stress) caused the failure? How can the failure occur? What could cause the part to fail? Why could the failure occur? Are there possible system interactions, operating environments, customer usages that could cause the failure? Examples: Stresses acting upon the part/system Thermal Shock Physical Shock Heat/Cold Soak For each cause identified, ask further whys in the direction of isolating root cause. RAM VIII Training Summit November 3-4, 2015
6
RAM VIII Training Summit
Failure Modes (How) Questions: What are the results of the Failure Mechanism acting upon the part? How did the part fail because of the failure mechanism? How could the part fail to perform its intended function? What could go wrong with this part ? What has gone wrong with this part in the past? How could the part be abused or misused? What concerns do you have with this design/ part? Examples: Change in shape Strain, flexure, bending Change in geometry Crack initiation & propagation, fracture, wear-out, pitting, galling Change in material properties Corrosion, intermetallic compounds, embrittlement, UV decay In what way could the item perform an unintended function? What could go wrong at the interfaces? Change in shape Strain, flexure, bending Change in geometry Crack initiation & propagation, fracture, wear-out, pitting, galling Change in material properties Corrosion, intermetallic compounds, molecular damage to polymer chains, embrittlement, UV decay RAM VIII Training Summit November 3-4, 2015
7
Failure Effects (Results)
Questions: What happens to the part with that failure mode? What happens to the system with that failure mode? Examples: Part: Light doesn’t work System: Performs its intended function In what way could the item perform an unintended function? What could go wrong at the interfaces? Change in shape Strain, flexure, bending Change in geometry Crack initiation & propagation, fracture, wear-out, pitting, galling Change in material properties Corrosion, intermetallic compounds, molecular damage to polymer chains, embrittlement, UV decay RAM VIII Training Summit November 3-4, 2015
8
Source of Failure Mechanisms
FMEA Template Part Nomenclature Source of Failure Mechanisms Failure Mechanism Failure Modes Failure Effects Part Transportation Storage Operation Ambient RAM VIII Training Summit November 3-4, 2015
9
Reliability Block Diagram
Part 3.1 Part 1 Part 2 Part 4 Part 3.2 Part 5 Part 6 Part 7 RAM VIII Training Summit November 3-4, 2015
10
RAM VIII Training Summit
Critical Items List Part Operating Condition MTBF Reliability Year 1 Year 3 Part 1 -55°C - 125°C Part 2 -60°C - 105°C Part 3.1 -40°C - 85°C Part 3.2 Part 4 -55°C °C Part 5 -65°C - 150°C Part 6 Part 7 RAM VIII Training Summit November 3-4, 2015
11
MTBF Determination MIL-HDBK 217
Results Parameter Value λp Failures/106 Hours MTBF e+11 hours FIT Failures/109 Hours RAM VIII Training Summit November 3-4, 2015
12
Reliability Equations
FIT – Failures per Billion hours Failure Rate (Landa) Reliability Equation RAM VIII Training Summit November 3-4, 2015
13
RAM VIII Training Summit
MTBF Determination Part Operating Range FIT MTBF (Hrs) λ 1 3 5 Part 1 -55°C - 125°C 269.60 4.64E+05 2.16E-06 0.9813 0.9449 0.9098 Part 2 -60°C - 105°C 299.18 1.11E+06 8.98E-07 0.9922 0.9767 0.9614 Part 3.1 -40°C - 85°C 368.07 1.36E+06 7.36E-07 0.9936 0.9808 0.9683 Part 3.2 557.09 1.80E+06 5.57E-07 0.9951 0.9855 0.9759 Part 4 -55°C °C 685.37 7.30E+05 1.37E-06 0.9881 0.9646 0.9417 Part 5 -65°C - 150°C 395.13 8.44E+05 1.19E-06 0.9897 0.9693 0.9494 Part 6 331.68 6.03E+05 1.66E-06 0.9856 0.9573 0.9299 Part 7 408.05 1.23E+06 8.16E-07 0.9929 0.9788 0.9649 RAM VIII Training Summit November 3-4, 2015
14
RAM VIII Training Summit
Weak Links Operating Conditions Parts not rated for stated conditions of use Low MTBF Components that are not redundant RAM VIII Training Summit November 3-4, 2015
15
RAM VIII Training Summit
Testing Failure Mechanisms Heat / Cold Physical Shock Vibration Thermal Shock Humidity Corrosion Equipment Used for Testing Fatigue Testing - Instron HALT chamber Thermal Shock Cyclic Corrosion Chamber Drop Test Altitude Chamber Dynamic Vibration System Environmental Chamber RAM VIII Training Summit November 3-4, 2015
16
RAM VIII Training Summit
OC Curves Number of Tests Needed # of Failures χ2 T n = 3 n = 5 n = 7 n = 10 n = 15 4.605 62170 863 518 370 259 173 1 7.779 105022 1459 875 625 438 292 2 10.645 143703 2994 1497 998 665 428 3 13.362 180381 7516 2505 1503 939 578 4 15.987 215827 4496 2248 1285 749 5 18.549 250416 10434 3478 1739 949 TABLE. OC Curves. θLCL = 27,000 hrs (3.080 years) α = 0.1 for Confidence RAM VIII Training Summit November 3-4, 2015
17
RAM VIII Training Summit
Questions RAM VIII Training Summit November 3-4, 2015
Similar presentations
