Eddy Current Test Method for Residual Stress in Non-Ferromagnetic Metal Objects

Author:  Jack A. Soules
Source:  US Patent 5,610,515
Doc ID:  1997035
Year of Publication:  1997
Abstract:  
A novel test method enabling residual stress in non-ferromagnetic metal objects to be reliably measured which requires particular circuit elements in the alternating current bridge circuit being employed for measurement to be environmentally controlled. In doing so, the selected circuit resistor elements are thermally isolated in a manner enabling lift-off impedance values to non-destructively measure near-surface residual stress in the metal object being tested.