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Full-Text Articles in Physics

Self-Consistent Swept Frequency Eddy Current Measurements For Characterization Of Near Surface Material Conditions, Chester C.H. Lo, Anatoli M. Frishman, Y. Shen, Norio Nakagawa Jul 2008

Self-Consistent Swept Frequency Eddy Current Measurements For Characterization Of Near Surface Material Conditions, Chester C.H. Lo, Anatoli M. Frishman, Y. Shen, Norio Nakagawa

Center for Nondestructive Evaluation Conference Papers, Posters and Presentations

This paper reports on a self‐consistent, swept frequency eddy current (SFEC) technique for characterizing surface and sub‐surface conditions of materials, with specific applications to detecting residual stresses in shot‐peened Ni‐base superalloys and surface oxidation in engineering components. The technique involves measuring lift‐off normalized vertical component signal to suppress lift off noise and instrumentation effect. Theoretical study shows that the vertical component signals are insensitive to coil dimensions, thus enabling EC measurements in separate frequency bands using multiple coils, while yielding continuous broad‐band data so that both the bulk conductivity and near‐surface conductivity profile ...


A Scaling Law For Nondestructive Evaluation Of Shot Peening Induced Surface Material Property Deviations, Anatoli M. Frishman, Chester C.H. Lo, Y. Shen, Norio Nakagawa Jul 2008

A Scaling Law For Nondestructive Evaluation Of Shot Peening Induced Surface Material Property Deviations, Anatoli M. Frishman, Chester C.H. Lo, Y. Shen, Norio Nakagawa

Center for Nondestructive Evaluation Conference Papers, Posters and Presentations

Shot peening is frequently used to improve mechanical characteristics of metallic components’ surfaces. The physical properties of shot peened surfaces exhibit deviations from their bulk values. This paper shows that there exists a scaling law (universality) among seemingly unrelated material property deviations and among different peening conditions. We present examples and support for scaling behaviors based on experimental data on Almen strip deflection, cold work and residual stress profiles of a shot peened nickel‐base superalloy (Waspaloy), and swept frequency eddy current signals used for NDE studies of another shot peened nickel‐base superalloy (Inconel 718). In addition, a fast ...