Case Studies of Fatigue Life Improvement Using Low Plasticity Burnishing in Gas Turbine Engine Applications

Paul S. Prevéy, President, Director of Research, Lambda Research, Inc.
Ravi A. Ravindranath, Propulsion & Power, Naval Air Systems Command (NAVAIR)
Dr. Michael J. Shepard, Materials Research Engineer, AFRL/MLSC
Dr. Timothy Gabb, NASA Glenn Research Center

Surface enhancement technologies such as shot peening, laser shock peening (LSP), and low plasticity burnishing (LPB®) can provide substantial fatigue life improvement. However, to be effective, the compressive residual stresses that increase fatigue strength must be retained in service. For successful integration into turbine design, the process must be affordable and compatible with the manufacturing environment. LPB® provides thermally stable compression of comparable magnitude and even greater depth than other methods, and can be performed in conventional machine shop environments on CNC machine tools. LPB® provides a means to extend the fatigue lives of both new and legacy aircraft engines and ground-based turbines. Improving fatigue performance by introducing deep stable layers of compressive residual stress avoids the generally cost prohibitive alternative of modifying either material or design.