Component Surface Treatments for Engine Fatigue Enhancement

"The 4th stage compressor IBR of the JSF F119 engine is fatigue limited. Surface enhancement, by the introduction of compressive residual stress, is a practical means of improving fatigue performance without changing material or design. Low PlasticityBurnishing (LPB) provides twice the HCF strength and four times the damage tolerance of shot peening in Ti-64 and IN718 laboratory specimens. LPB applied to the leading edge of the F404 Ti-64 1st stage fan blade has been shown to produce sufficientthrough-thickness compression for complete tolerance of 1.3 mm (0.050 in.) deep FOD. LPB offers rapid, affordable, surface enhancement using conventional CNC machine tools in a manufacturing environment.With the support of Pratt and Whitney, the feasibility of improving damage tolerance of the F119 4th stage compressor IBR blades with LPB processing will be investigated. LPB parameters and control software will be developed using existing tooling and4-axis CNC facility. The HCF life and damage tolerance achievable with LPB will be documented and compared to the current practice of shot peening. Phase II will thoroughly document HCF performance of LPB processed blades, and address the development of anautomated production facility for LPB processing full IBRs in manufacturing and repair. The immediate anticipated benefit of the proposed effort to the Air Force is elimination of the fatigue related performance limitations imposed on the F119