Sourcemat

Turbine rotor material design : phase II

Abstract : The Federal Aviation Administration (FAA) is working with the aircraft engine industry to develop an enhanced life management process, based on probabilistic damage tolerance principles, to address the threat of material or manufacturing anomalies inhigh-energy rotating components, and the process is documented in current and planned versions of FAA Advisory Circular (AC) 33.14. An integrated team of Southwest Research Institute, GE Aviation, Pratt & Whitney, Honeywell, and Rolls-Royce Corporation has developed enhanced predictive tool capability and supplementary material/anomaly behavior characterization and modeling to support and enhance the process and the AC. Sensitivity studies were performed to guide a planned update of the hard alpha (HA) anomaly distributions. A computer code was developed to describe the diffusion of nitrogen or oxygen in titanium (Ti) from an inclusion during melting and heat treatment. The DEFORM™ forging microcode was validated experimentally and used to study cracking of HA anomalies during forging. Ultrasonic inspection methods were evaluated at the billet and forging stages. The influence of elevated oxygen on Ti-17 was evaluated with tensile and fatigue tests. Spin pit and coupon experiments were conducted to study the fatigue behavior of embedded HA. Vacuum fatigue crack growth (FCG) data were generated for three nickel alloys and Ti-6242. Thermomechanical FCG behavior was studied in IN-718. A literature survey was conducted on the stability and significance of surface residual stresses in fatigue. New DARWIN® versions were developed to address anomalies associated with surface damage in three-dimensional (3D) components and different types of inherent anomalies (including large numbers of 3D anomalies and nonnegligible crack formation lives). Enhancements in the probabilistic methods and many other new capabilities were developed to improve the overall efficiency and accuracy of the risk assessment computations in DARWIN. The partnered engine companies verified the accuracy and usability of DARWIN. A three-day DARWIN training workshop was conducted. An infrastructure was developed to support code licensing and distribution for users employing DARWIN