Turbine Rotor Material Design
Abstract
Premium grade titanium alloys are used for fan and compressor rotors and disks in aircraft turbine engines. Occasional upsets during processing can result in the formation of metallurgical anomalies referred to as hard alpha (HA). Although rare, low-cycle fatigue cracks initiated by HA have led to uncontained engine failures that resulted in fatal accidents such as the incident at Sioux City, Iowa, in 1989. In a report issued by the Federal Aviation Administration (FAA) after the accident at Sioux City, it was recommended that a damage tolerance approach be implemented to explicitly address HA anomalies, with the objective of enhancing conventional rotor life management methodology. The probabilistic, damage tolerance code developed in this program for low-cycle fatigue of titanium rotors/disks is intended to supplement, not replace, the current safe-life design. The code is called Design Assessment of Reliability With INspection (DARWIN) and was developed in collaboration with AlliedSignal Engines, General Electric Aircraft Engines, Pratt & Whitney, and Rolls-Royce Allison. DARWIN integrates finite element stress analysis, fracture mechanics analysis, nondestructive inspection simulation, and probabilistic analysis to assess the risk of rotor fracture. Supplementary tasks performed in this program in support of code implementation included the generation of fatigue crack growth data for Ti-64, Ti-6242, and Ti-17beta in high vacuum; determination of the crack initiation behavior of artificial and natural HA defects embedded in plates of Ti-64; and development of a forging microcode to predict the movement, shape and orientation of HA anomalies during processing from ingot to billet, and from billet to a disk forging.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 2000
- Accession Number
- ADA388174
Entities
People
- C. Fischer
- G. G. Chell
- G. R. Leverant
- M. P. Enright
- R. C. Mcclung
Organizations
- Southwest Research Institute