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NONDESTRUCTIVE EVALUATION OF NEAR-SURFACE RESIDUAL STRESS IN SHOT-PEENED NICKEL-BASE SUPERALLOYS

YU, FENG
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1130282650

Abstract Details

2005, PhD, University of Cincinnati, Engineering : Aerospace Engineering.
Surface enhancement methods, which produce beneficial compressive residual stresses and increased hardness in a shallow near-surface region, are widely used in a number of industrial applications, including gas-turbine engines. Nondestructive evaluation of residual stress gradients in surface-enhanced materials has great significance for turbine engine component life extension and their reliability in service. It has been recently found that, in sharp contrast with most other materials, shot-peened nickel-base superalloys exhibit an apparent increase in electrical conductivity at increasing inspection frequencies, which can be exploited for nondestructive residual stress assessment.The primary goal of this research is to develop a quantitative eddy current method for nondestructive residual stress profiles in surface-treated nickel-base superalloys. Our work have been focused on five different aspects of this issue, namely, (i) validating the noncontacting eddy current technique for electroelastic coefficients calibration, (ii) developing inversion procedures for determining the subsurface residual stress profiles from the measured apparent eddy current conductivity (AECC), (iii) predicting the adverse effect of surface roughness on the eddy current characterization of shot-peened metals, (iv) separating excess AECC caused by the primary residual stress effect from intrinsic conductivity variations caused by material inhomogeneity, and (v) investigating different mechanisms through which cold work could influence the AECC in surface-treated nickel-base superalloys. The results of this dissertation have led to a better understanding of the underlying physical phenomenon of the measured excess AECC on nickel-base engine alloys, and solved a few critical applied issues in eddy current nondestructive residual stress assessment in surface-treated engine components and, ultimately, contributed to the better utilization and safer operation of the Air Force’s aging aircraft fleet.
Dr. Peter Nagy (Advisor)
210 p.
Engineering, Aerospace
NDE; Eddy Current; Residual Stress; Shot Peening; Engine Alloy

Recommended Citations

Citations

  • YU, F. (2005). NONDESTRUCTIVE EVALUATION OF NEAR-SURFACE RESIDUAL STRESS IN SHOT-PEENED NICKEL-BASE SUPERALLOYS [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1130282650

    APA Style (7th edition)

  • YU, FENG. NONDESTRUCTIVE EVALUATION OF NEAR-SURFACE RESIDUAL STRESS IN SHOT-PEENED NICKEL-BASE SUPERALLOYS. 2005. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1130282650.

    MLA Style (8th edition)

  • YU, FENG. "NONDESTRUCTIVE EVALUATION OF NEAR-SURFACE RESIDUAL STRESS IN SHOT-PEENED NICKEL-BASE SUPERALLOYS." Doctoral dissertation, University of Cincinnati, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1130282650

    Chicago Manual of Style (17th edition)

ucin1130282650
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© 2005, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.