ULTRASONIC PULSED-BEAM INTERACTION WITH A FLUID-LOADED ELASTIC PLATE - EXPERIMENTAL VALIDATION

In this paper, the analytical model developed in the preceding paper [ S. Zeroug and F. E. Stanke, ''Ultrasonic pulsed beam interaction with a fluid-loaded elastic plate: Theory,'' J. Acoust. Sec. Am. 100, xx-xx (1996)] is numerically implemented and experimentally validated for u ltrasonic transducer-excited pulsed beams interacting with a fluid-loa ded elastic plate. Using flat piston ultrasonic transducers, two modes of operation are considered: (1) a transmission mode using a pair of transducers and (2) a reflection mode at normal incidence with a singl e transducer (i.e., pulse echo). A first algorithm, based on real-axis integration (RAI) of the original beam integrals, is used to generate reference data in both modes of operation and is validated by compari son with experiments on various plates. A more computationally efficie nt algorithm, based on the multiply reflected asymptotic-beam (MRAB) a pproach, and compared with experiments and RAI data, works accurately for signals from thick plates (in terms of the plate compressional wav elength at the signal center frequency). In particular, it validates t he higher-order asymptotic expansion for shear waves excited at normal incidence. However, the MRAB algorithm fails for thin plates mainly i n the low-frequency range of the signal. The results attained in this study suggest a rule of thumb that scattered signals comprised of reso lvable arrivals are amenable to modeling with the MRAB approach. (C) 1 996 Acoustical Society of America.