Table 1 Historic failures and their impact on life assessment concerns Failure I Year Reason for failu Life assessment developments Titanic(Ref 4) 1912 Ship hits iceberg and watertight Improvement in steel grades compartments rupture Safety procedures established for lifeboats Warning systems established for Molasses Tank Failures 1919, Brittle fracture of the tank as a result of poor Design codes for storage tanks (Ref 5) 1973 ductility and higher loads Consideration give to causes for Tacoma Bridge Failure 1940 Aerodynamic instability and failure caused Sophisticated analytical models (Ref 6, 7 by wind vortices and bridge desi developed for resonance Bridge design changed to account for World War II Liberty 1942- 1289 of the 4694 warships suffered brittle Selection of increased toughness ships (ref 8) 1952 fracture or structure failure at the welded mater Improved fabrication practices Development of fracture mechanics Liquefied natural gas 1944 Failure and explosion of an LNG pressure Selection and development of (LNG) storage tank vessel due to a possible welding defect and materials with improved toughness at (Ref 9) improperly heat treated material resulting in the service temperature of-160C( obsequent fatigue crack growth 250°F) Comet aircraft failures 1950s Fatigue crack initiation in pressurized skins Development of the fatigue"safe-life" (Ref 10) due to high gross stresses and stress concentration effects from geometric features Evaluation of the effects of geometry Evaluation of the effects of stiffeners on stress distribution Establishment of aircraft structural gram(ASIP)in 1958 F-111 Aircraft No 94 1969 Fatigue failure due to material defect in Improved inspection techniques wing pivot fitting(Ref high-strength steel l1) damage-tolerant design philosophy relopment of materials with Seam-welded high- 1986- Cavitation and creep voids in welds Development of elevated-temperature energy piping failures 2000 resulting in catastrophic high-energy rupture life assessment techniques for (Ref 12 cavitation and creep failure Aloha Incident, Boeing 1988 Accelerated corrosion and multiple fatigue Improved aircraft maintenance and 737(Ref13) crack-initiation sites in riveted fuselage skin inspection procedures Life assessment methods developed Sioux City Incident 1989 Hard alpha case present in titanium fan disk Increased process controls on (Ref 14) resulted in fatigue crack initiation and processing of titanium ingots catastrophic failureTable 1 Historic failures and their impact on life assessment concerns Failure Year Reason for failure Life assessment developments Titanic (Ref 4) 1912 Ship hits iceberg and watertight compartments rupture. Improvement in steel grades Safety procedures established for lifeboats Warning systems established for icebergs Molasses Tank Failures (Ref 5) 1919, 1973 Brittle fracture of the tank as a result of poor ductility and higher loads Design codes for storage tanks developed Consideration given to causes for brittle fracture Tacoma Bridge Failure (Ref 6, 7 1940 Aerodynamic instability and failure caused by wind vortices and bridge design Sophisticated analytical models developed for resonance Bridge design changed to account for aerodynamic conditions World War II Liberty ships (Ref 8) 1942– 1952 1289 of the 4694 warships suffered brittle fracture or structure failure at the welded steel joints. Selection of increased toughness material Improved fabrication practices Development of fracture mechanics Liquefied natural gas (LNG) storage tank (Ref 9) 1944 Failure and explosion of an LNG pressure vessel due to a possible welding defect and improperly heat treated material resulting in subsequent fatigue crack growth Selection and development of materials with improved toughness at the service temperature of -160 °C (- 250 °F) Comet aircraft failures (Ref 10) 1950s Fatigue crack initiation in pressurized skins due to high gross stresses and stress concentration effects from geometric features Development of the fatigue “safe-life” approach Evaluation of the effects of geometry and notches on fatigue behavior Evaluation of the effects of stiffeners on stress distribution Establishment of aircraft structural integrity program (ASIP) in 1958 F-111 Aircraft No. 94 wing pivot fitting (Ref 11) 1969 Fatigue failure due to material defect in high-strength steel Improved inspection techniques Change from fatigue “safe-life” to damage-tolerant design philosophy Development of materials with improved toughness Seam-welded high￾energy piping failures (Ref 12) 1986– 2000 Cavitation and creep voids in welds resulting in catastrophic high-energy rupture Development of elevated-temperature life assessment techniques for cavitation and creep failure Aloha Incident, Boeing 737 (Ref 13) 1988 Accelerated corrosion and multiple fatigue crack-initiation sites in riveted fuselage skin Improved aircraft maintenance and inspection procedures Life assessment methods developed for multiple-site damage (MSD) Sioux City Incident (Ref 14) 1989 Hard alpha case present in titanium fan disk resulted in fatigue crack initiation and catastrophic failure. Increased process controls on processing of titanium ingots