Barkhausen noise gives information from the surface and very close area beneath the surface. Compressive stresses will decrease the intensity of Barkhausen noise while tensile stresses increase it. This fact can be exploited so that by measuring the intensity of Barkhausen noise the amount of residual stress can be determined.
Barkhausen Noise Analysis (BNA) is based on a concept of inductive measurement of a noise-like signal, generated when a magnetic field is applied to a ferromagnet.
Advanced stress testing technology for shot peened surfaces. Interview with Dominik Dapprich, Managing Director of Stresstech GmbH MFN international Vol. 18, July Issue, Year 2017
Shot peening produces compressive stresses to the surface of the workpiece, thus making it more durable. A common technique for measuring residual stresses of shot-peened workpieces is X-ray diffraction. The Xstress Robot system uses an industrial robot as a goniometer, thus bringing more flexibility and automation to measurement processes.