AO Lamb Mode Radiation Characteristics of Air-Coupled Transducers in Isotropic Plates

The fundamental anti-symmetric Lamb mode (A(o)) radiation characteristics of air-coupled transducers in isotropic (aluminium) plates were measured experimentally for the first time. To evaluate the radiation characteristics, experiments were performed by fixing the position of one of the transducers (either transmitter or receiver) and then moving other one (either receiver or transmitter) along the circumference of a circle, whose radius was equal to that of the distance of separation between the transducers. Experiments were conducted to evaluate the radiation pattern of 100 kHz, 200 kHz and 500 kHz air-coupled transducers in one mm and three mm thick aluminium plates. It is interesting to note that, Ao Lamb mode radiation pattern emitted by air-coupled transducers in isotropic plates is characterised by Gaussian curve.