Magnetic Barkhausen noise and acoustoelasticity: A comparison of two non-destructive methods of measuring residual stresses

Residual stress in various samples was investigated using two unconventional and non-destructive methods. These methods consist of a magnetic technique based on Magnetic Barkhausen Noise (MBN) and acoustoelasticity, an ultrasonic technique using surface and shear waves generated with EMATs (Electromagnetic Acoustic Transducers).; MBN measurements were performed on structural steel samples. Applied stress magnitudes were correlated to MBN energy levels for calibration purposes. MBN energy measurements were obtained from steel samples and residual stress results were found using the calibration curves. The effect of certain parameters on the calibration curves were examined and discussed. The validity of the residual stress results was confirmed experimentally using conventional methods: cutting and sectioning and X-Ray diffraction. It was found that MBN yielded quantitative results which were very similar to those obtained with the conventional methods. The possible sources of residual stresses and their distribution on the structural steel specimens were discussed.; Applied stress in aluminium was correlated to ultrasonic surface wave velocity and residual stresses were determined in aluminium samples using this information. Shear horizontally polarized waves (SH waves) were tentatively used to measure stress states in plates of steel and aluminium and in the structural steel samples. Texture orientation distribution coefficients (ODC) were calculated using the SH{dollar}sb0{dollar} plate mode in steel and aluminium plates. (Abstract shortened by UMI.)...