Na. Schumacher et al., A LASER-BASED INVESTIGATION OF HIGHER-ORDER MODES IN TRANSIENT LAMB WAVES, The Journal of the Acoustical Society of America, 93(5), 1993, pp. 2981-2984
This Letter describes the integration of laser and fiber optic methods
for generating and detecting broadband, transient Lamb waves in a ste
el plate. The generated Lamb waves are shown to be a superposition of
different Lamb modes including the zeroth-order symmetric together wit
h the zeroth- and first-order antisymmetric modes. Signal processing t
echniques are used to extract the phase velocities for each of these m
odes over a continuous, broadband frequency spectrum from the transien
t time histories of the waves recorded at two locations on a steel pla
te. The results are found to be in excellent agreement with theoretica
l phase velocities for each of the three modes evaluated.