Stress Measurement of Thin-Walled Parts Based on SH Guide Wave EMATs

Ultrasound is widely used for non-destructive testing to measure stress. In comparison to piezoelectric ultrasound, electromagnetic ultrasound provides benefits such as non-coupling and non-contact, and it can measure stress in complex on-site environments. Shear-Horizontal (SH) guide wave is one of the important waveforms propagating in thin-walled parts, which can still exist in zero-order symmetric mode in long-distance propagation. However, most studies now use SH guided waves to measure defects, few studies use SH guided waves to measure stress. Hence, a stress measurement model for a periodic permanent magnet electromagnetic acoustic transducer (EMAT) is established in this paper based on the advantages of SH guided wave propagation in thin-walled components. After that, a finite element model of a periodic permanent magnet electromagnetic acoustic transducer is developed to study the propagation law of SH guided waves. Finally, the designed SH guided-wave periodic permanent magnet EMAT is used to conduct tensile stress measurement experiments, and the test results showed that the measured stresses were in good agreement with the real stresses, which verified the feasibility of the designed transducer and measurement method.