A new method for plastic strain measurement with Rayleigh wave polarization.

In this work, a new non-contact and coupling-free ultrasound method with measuring Rayleigh wave polarization (RWP) by electromagnetic acoustic transducers (EMATs) is applied for plastic strain measurement, which can provide a very promising alternative and reference-free ultrasonic testing technique with high spatial resolution. Two specially designed EMAT receivers are developed to measure the polarization of Rayleigh wave generated by an enhanced meander-line-coil EMAT. The change in RWP due to the plastic strain has been successfully measured. And the measurement results indicate that the plastic strain at the specimen surface can be evaluated with good accuracy by measuring the relative change in RWP with the proposed EMAT-based method.