Test of a bond-correction formula for ultrasonic velocity measurement

A formula for the shift of a resonance frequency induced by a bond of nonvanishing thickness is tested. Experiments are performed on a solid rod of polycrystalline nickel that is machined into three segments, representing specimen, bond, and transducer. Acoustic waves are launched and detected magnetostrictively. Measured patterns of frequency shift vs. frequency for various lengths and diameters of the bond exhibit satisfactory agreement with predictions. The patterns provided physical insight into the interaction between specimen, bond, and transducer, and they indicate the importance of assessing the full pattern to determine accurate values of velocity in continuous-wave ultrasound experiments.<
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