Attenuation measurement of cylindrical guided waves

Guided waves can propagate along waveguides with low attenuation. Therefore, guided waves are expected to be used for non-destructive testing especially of cylindrical structures such as wire-ropes. However, as guided waves propagate over longer distance, their attenuation cannot be neglected, though quantitative measurement of attenuation of cylindrical guided waves has not yet been given enough. Thus, we conducted theoretical analysis and experiment of wave attenuation. In theoretical analysis, we derived dispersion curves including effects of material attenuation in order to obtain frequency-dependent attenuation coefficients. In experiment, we transmitted and received guided waves by electromagnetic acoustic transducers (EMATs) in order to measure attenuation of guided waves. By comparing the experimental results with the theoretical ones, we showed that the experimental results of wave attenuation increased with frequency just as the theoretical ones, though the formers were larger than the latters.