The optimization of lamb and Rayleigh wave generation using wideband-low-frequency EMATs

This paper describes a non-contact ElectroMagnetic Acoustic Transducer (EMAT) that can be used to generate both Lamb and Rayleigh waves on metal samples. The generated waves are wideband and low frequency with a dominant frequency content centred on approximately 200kHz extending to around 500kHz. Detection of the waves is achieved using a linear coil detection EMAT. The transducers (generator & detector) have been used on both aluminium and steel, but operate more efficiently on aluminium due to its lower electrical resistance and density when compared to steel. Some considerations are described for the design of the generation EMAT including applications where the dynamic field from the coil alone is used to obtain the Lorentz interaction with the sample surface eddy current.