Turbine Rotor Material Design
Program Team:
General Electric
Honeywell
Pratt & Whitney
Rolls-Royce
Southwest Research Institute
Sponsor: Federal Aviation Administration
FAA Technical Monitor: Joe Wilson
SwRI Program Manager: Gerald Leverant
5th Annual FAA/Air Force/NASA/Navy Workshop:
Application of Probabilistic Methods to Gas Turbine Engines
June 12, 2001
d:/data/leverant/trmd-June01.ppt
Turbine Rotor Material Design
Program Goals
! Develop a probabilistically-based damage tolerant design
code to augment the current safe-life philosophy for life
management of commercial aircraft gas turbine rotors and
disks.
! Provide supplementary material/anomaly characterization
and modeling to support the enhanced life management
process.
Industrialization of DARWIN™
! Engine manufacturers request that SwRI provide ongoing
support for DARWIN™.
! FAA grants intellectual property rights to SwRI.
! U. S. government receives royalty-free license.
! SwRI is providing full support and enhancements.
! Licensing to OEM’s is underway.
Turbine Rotor Material Design
! Phase I:
(8/95 - 9/99)
Hard alpha anomalies in titanium
! Phase II:
(4/99 - 3/04)
Hard alpha anomalies in titanium
Machining/maintenance-induced surface anomalies
Anomalies in cast/wrought and P/M nickel
Turbine Rotor Material Design
Background
! Periodic adverse events have been associated with
microstructural, manufacturing, and maintenance-induced
anomalies in aircraft gas turbine rotors/disks during the past
30-35 years.
! A commercial DC-10 airliner crash-landed at Sioux City, IA, in
1989 as a result of an uncontained titanium fan disk failure
attributed to a hard alpha inclusion.
! In 1990, the “FAA Titanium Rotating Component Review Team
Report” recommended consideration of incorporating risk
management and damage tolerance concepts into design
procedures for critical, high energy components in commercial
engines.
! The AIA Rotor Integrity Subcommittee (RISC) was formed in
1991 to implement these recommendations.
Turbine Rotor Material Design
Program Motivation
! The current safe-life philosophy for life management of
rotors/disks does not account for undetected material,
manufacturing, and maintenance-induced anomalies.
! As RISC formulated an enhanced life management process
based on probabilistic damage tolerance methods and
employing opportunity inspections, it became apparent that the
emerging process could be significantly enhanced by R&D that
addressed identified shortfalls in technology and data.
! The enhanced predictive tool capability and supplementary
material/anomaly behavior characterization and modeling
derived from the R&D program will provide direct support for
the implementation of FAA Advisory Circular 33.14 and for
additional improvements in those guidelines.
Turbine Rotor Material Design
Accomplishments to Date
! A probabilistic design code (DARWIN™) has been developed for hard
alpha in titanium that integrates finite element stress analysis, fracturemechanics-based LCF life assessment, material anomaly size
distributions, probability of anomaly detection by NDE, and inspection
schedules to compute the risk of rotor disk failure. The FAA has stated
that use of DARWIN™ is an acceptable means of compliance with
AC33.14. Enhancement of the code to handle machining and
maintenance-induced surface anomalies in all disk alloys is underway.
! Vacuum fatigue crack growth data have been obtained for Ti-64, Ti6242,
and Ti-17 as a function of temperature and mean stress (R). Work is
underway on IN718 and Waspaloy.
! Monotonic and cyclic crack initiation and early crack growth data on
specimens and LCF life data on spin-pit-tested disks have been obtained
on Ti-64 containing seeded and natural hard alpha anomalies of various
nitrogen contents. Additional specimen testing is underway.
Turbine Rotor Material Design
Accomplishments to Date
! A deformation microcode has been developed and integrated with
the commercially-available DEFORM™ forging code. The
integrated product is intended for predicting the change in shape
and orientation of hard alpha anomalies of various nitrogen contents
during material reduction from ingot to billet to final forged product.
Validation of the code is underway based on the results of forging
trials conducted on seeded billets.
! A code, called GROW, has been developed to predict the
dissolution rate of hard alpha in liquid titanium. Calibration of the
code is underway.
! Extensive UT NDE data has been generated on billets, pancake
forgings, disk forgings, and semi-finished spin pit disks containing
seeded and natural hard alpha anomalies.
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