Ultrasonic pulsed beam interaction with a fluid‐loaded elastic plate: Theory

The interaction of transducer‐excited ultrasonic pulsed beams with fluid‐loaded elastic plates is treated with a computationally efficient analytical model. The model synthesizes the frequency‐domain voltage, due to a single transducer operated in reflection (pulse‐echo) mode and a pair of tranducers in transmission mode, utilizing an approach that is based on (1) expansion of transducer fields in terms of quasi‐Gaussian beams modeled via the complex‐source‐point technique and its recent extension to finite receivers, and on (2) complex wave‐number spectral decomposition and synthesis to solve the beam–structure interaction problem. First, a reference solution for the frequency‐domain reflected and transmitted fields is expressed in terms of spectral integrals over two‐dimensional infinite spectra of plane waves weighted by the plate reflection or transmission coefficient. Subsequent expansion in terms of a finite sum of integrals representing multiply reflected beams propagating within the plate, combine...