Stress Measurement of Ferromagnetic Materials Using Hybrid Magnetic Sensing

Stress measurement and evaluation of ferromagnetic components using electromagnetic nondestructive testing (ENDT) are affected by the microstructure properties of the material, such as inhomogeneity and anisotropy. This leads to magnetic induction sensitivity in the variety of both the stress and microstructure. To address this challenge, a hybrid magnetic sensing structure for measuring eddy current (EC), alternating electromagnetic (EM) field, Barkhausen noise, and incremental permeability signals is designed and instrumented. Additionally, a stress detection verification test for oriented silicon steel samples is carried out, and a comparison with commercial instruments in terms of sensitivity and repeatability is performed. The results show that the proposed sensor has advantages in detection repeatability, good sensitivity as well as high signal-to-noise (SNR) for MBN features, which brings potential in stress characterization and assessment.