Quantitative modeling of the transduction of electromagnetic acoustic transducers operating on ferromagnetic media

摘要: The noncontact nature of electromagnetic acoustic transducers (EMATs) offers a series advantages over traditional piezoelectric transducers, but these features are counter-balanced by their relatively low signal-to-noise ratio and strong dependence on material properties such as electric conductivity, magnetic permeability, magnetostriction. implication is that full exploitation EMATs needs detailed modeling operation. A finite element model, accounting for the main transduction mechanisms, has been developed to allow optimization transducers. Magnetostriction included described through an analogy with piezoelectricity. model used predict performance simple EMAT: single current-carrying wire, parallel bias field generating shear horizontal waves in nickel plate close it. results validated against experiments. able successfully wave amplitude significant parameters: static field, driving current amplitude, excitation frequency. comparison does not employ any arbitrary adjustable parameter; first time absolute validation magnetostrictive EMAT achieved. satisfactory: discrepancy between numerical predictions measured values per unit less than 20% 200 kHz frequency range. study also shown sensitivity only function properties, because permeability plays role mechanism, partly counterbalancing effects.