Detection of residual stresses with impedance spectroscopy: A novel approach

This study explored the relationship between residual stress and impedance in Hastelloy-X, Ti6Al4V, and Inconel-718 materials using the electromechanical impedance spectroscopy technique with normal and shear horizontal piezoelectric sensors. Root mean square deviation values, calculated from reactance measurements, were compared with normal and shear stresses. The results revealed strong correlations, with coefficients of 0.9, -0.89, and -0.88 between root mean square deviation and maximum normal stress (MPa) for Ti6Al4V, Inconel-718, and Hastelloy-X, respectively. Similar correlations were found for 45-degree shear stress (MPa), with coefficients of 0.9, -0.96, and -0.88. The regression analysis indicated that second- and third-degree equations best fit the correlation between maximum normal stress (MPa) and root mean square deviation, while third-degree equations were optimal for 45-degree shear stress (MPa) and root mean square deviation. These findings highlight the sensitivity and potential of the electromechanical impedance spectroscopy technique for non-destructive residual stress evaluation.