Enhanced Life Prediction Methodologies for Engine Rotor Life Extension, 18-9414Printer Friendly Version
Inclusive Dates: 07/16/03 - Current
Background - The U.S. Air Force (USAF) is facing a potentially large wave of turbine engine disc replacement costs over the next 8 to 10 years that are inconsistent with anticipated budgets. Consequently, the Engine Rotor Life Extension (ERLE) program was conceived by the Air Force Research Laboratory (AFRL) as a sound science and technology investment that offers the potential for significant cost-avoidance by extending the life of certain life-limiting components. The concept is to extend the life of these components by recovering the conservatism believed to exist in design and life management practices, without increasing risk, by systematically improving and more effectively integrating a number of life management technologies-life prediction, nondestructive inspection, engine health monitoring, maintenance and repair. Southwest Research Institute® (SwRI®) is leading a team with unique capabilities to enhance, as well as integrate, several of the above life management technologies. Other team members include Smiths Aerospace, The University of Texas at San Antonio, and Mustard Seed Software.
Studies by the USAF and engine manufacturers have estimated that successful science and technology investments of this type could reduce the disk replacement costs by 50 percent, which would amount to a cost savings of $600 million over five years. Enhancements in engine life management technology would also be applicable to developmental and future engines. Similar benefits are also expected in the commercial sector, where safety, reliability, and cost of ownership are of paramount importance. The technologies and software to be developed in this program are also expected to be of value to the power generation industry where availability and cost of ownership are high priorities, particularly in the deregulated market.
Approach - The approach and technical objectives of this program are to develop and demonstrate: 1) a new family of physically-based, deterministic life prediction models for treating total fatigue life including crack nucleation, microcrack growth and large crack growth; 2) an efficient probabilistic life prediction methodology based on the stochastic nature of each of the above phases of fatigue life; and 3) a methodology for enhanced engine life management based on hybridisation of state-of-the-art probabilistic life prediction and classical engine health monitoring.
Accomplishments - Effort during the initial few months of this recently initiated program have focused on the development of methods to transform engine sensor data (rotor speed) into stress within the engine discs-one of the most fracture critical components of the engine. Application of parallel processing computing methods has also shown to result in significant efficiency increases during the computationally intensive probabilistic simulation. Synergisms have also been identified between classical diagnostic and prognostic methods and damage-based probabilistic life prediction. Engineering assessments of the significance of these synergisms are underway. This project has resulted in the award of a Dual Use Science and Technology Program from the Air Force Research Laboratory.