Forward to residual stress measurement by using pulsed eddy current technique

The presence of residual stress in any material can have an influence on its mechanical properties, such as creep or fatigue life. Two common non-destructive methods, X-ray diffraction and ultrasound, are not reliable methods for subsurface residual stress measurement and the destructive hole-drilling method is not absolutely precise and safe. Recently, the non-destructive eddy current method has been applied to residual stress estimation, but it is only useful for surface residual stress measurements. This paper presents an application of the pulsed eddy current (PEC) method for stress measurement. PEC, as a high- performance non-destructive testing technique, has greater penetration than the conventional eddy current technique. In this study, the capability of PEC for subsurface residual stress measurement is investigated. After acquiring the PEC response to applied stresses, signals are initially analysed in a qualitative manner. Then, by the application of signal processing methods to the PEC signals, a quantitative approach for measuring residual stress is developed. Finally, a calibration curve for an aluminium specimen is made after data classification using experimental test data. The error of estimating residual stress by the calibration curve is evaluated and results show the potential of the PEC method for residual stress measurement.