Verification of Probabilistic Life Prediction Codes

Structural Life and Reliability Metrics----Benchmarking andVerification of Probabilistic Life Prediction CodesJonathan S. LittArmy Research LaboratoriesGlenn Research CenterCleveland, Ohio 44135Sherry SoditusUnited AirlinesSan Francisco International AirportSan Francisco, California 94128Robert C. Hendricks and Erwin V. ZaretskyNASA Glenn Research CenterCleveland, Ohio 44135Over the past two decades there has been considerable effort by NASA Glenn and othersto develop probabilistic codes to predict with reasonable engineering certainty the lifeand reliability of critical components in rotating machinery and, more specifically, in therotating sections of airbreathing and rocket engines. These codes have, to a very limitedextent, been verified with relatively small bench rig type specimens under uniaxialloading. Because of the small and very narrow database the acceptance of these codeswithin the aerospace community has been limited. An alternate approach to generatingstatistically significant data under complex loading and environments simulating aircraftand rocket engine conditions is to obtain, catalog and statistically analyze actual fielddata. End users of the engines, such as commercial airlines and the military, record andstore operational and maintenance information. This presentation describes a cooperativeprogram between the NASA GRC, United Airlines, USAF Wright Laboratory, U. S.Army Research Laboratory and Australian Aeronautical & Maritime ResearchLaboratory to obtain and analyze these airline data for selected components such asblades, disks and combustors. These airline data will be used to benchmark and compareexisting life prediction codes.