Near point-source longitudinal and transverse mode ultrasonic arrays for material characterization

Specially constructed near point-source ultrasonic transducers (0.75 MHz) w ere designed to preferentially stimulate and receive the one longitudinal ( P) and two transverse (S) propagation modes. Arrays of these transducers we re placed on a rectangular prism of common soda-lime glass, which served as an ideal homogeneous, isotropic medium, to evaluate the uncertainty of a n ewly developed phase velocity measurement method. Through the use of the Ra don transform, the data were transformed from the offset-time (x-t) domain to the intercept time-horizontal slowness (tau -p) domain. From the shape o f the curves in the tau -p domain, the phase velocity of the propagating wa ves may be determined for a range of directions. The phase velocities deter mined using this method were accurate for incidence angles up to 76 degrees , 64 degrees, and 77 degrees for the P, SV, and SH wave modes, respectively . Phase velocities of 5724 +/- 64, 3411 +/- 30, and 3467 +/- 15 m/s were de termined for the P-wave, SV-wave, and SH-wave modes, respectively. This agr ees with the direct transmission P-wave and S-wave velocities of 5690 +/- 6 0 and 3440 +/- 26 m/s, respectively, to better than 1%.