A broadband, through-transmission technique is described that measures directly the change in phase velocity with frequency without first measuring the absolute phase velocity at different frequencies. The method only requires the measurement of the specimen’s thickness and recording of two pulses: one without and one with the specimen inserted between the transmitting and receiving transducers...

Surface acoustic wave (SAW) velocity spectroscopy has been long considered to be one of the leading candidates for nondestructive characterization of surface-treated metals because of its ability to probe the material properties at different penetration depths depending on the inspection frequency. We developed a high-precision laser-ultrasonic technique to study the feasibility of SAW dispersi...

There is growing interest in using seismic attenuation for reservoir characterization. We measure limestone samples in the laboratory to analyze attenuation and elastic moduli as a function of frequency from 3 Hz to ultrasonic. We observe that there is a positive correlation between bulk modulus dispersion and permeability. We also measure different modes of attenuation and find that the attenu...

Besides the phase and group velocities, the amplitude of guided wave mode is also frequency dependent. This amplitude dispersion also influences the performance of guided wave methods in nondestructive evaluation (NDE) and structural health monitoring (SHM). In this paper, the effects of amplitude dispersion to the spectrum and waveform of a propagating wave-packet are investigated. It is shown...

Sparse arrays of permanently attached ultrasonic transducers are capable of quickly interrogating large areas, thereby reducing or eliminating the need for extensive bulk wave testing in plate-like structures. Current imaging methods often ignore dispersion, analyzing received signals by approximating wave propagation with a nominal group velocity. Dispersion compensation can significantly impr...

This paper proposes a non-contact nondestructive evaluation (NDE) technique that uses laser-induced ultrasonic waves to visualize corrosion damage in aluminum alloy plate structures. The non-contact, pulsed-laser ultrasonic measurement system generates ultrasonic waves using a galvanometer-based Q-switched Nd:YAG laser and measures the ultrasonic waves using a piezoelectric (PZT) sensor. During...

Layered materials must be exfoliated and dispersed in solvents for diverse applications. Usually, highly energetic probe sonication may be considered to be an unfavourable method for the less defective exfoliation and dispersion of layered materials. Here we show that judicious use of ultrasonic cavitation can produce exfoliated transition metal dichalcogenide nanosheets extraordinarily dispers...

Lamb waves are often used in ultrasonic applications for non-destructive testing of large constructions. The difficulty in the analysis of Lamb waves is their dispersive characteristics, especially their frequency dependent phase and group velocities. This article focuses on the separation of the first symmetric mode S0 and the first asymmetric mode A0 and the reliable estimation of their group...

In the present study, dispersion and displacement curves of ultrasonic lamb wave, propagated in Aluminum thin plates, were drawn. Two ultrasonic lamb wave techniques, pulse-echo (a1 mode as emitter) and emission (s1 mode as emitter), were used for interpretation of notch defects with depths of 10%, 30% and 60% of plate thickness. Thickness of plate was 2 mm and the nominal centre frequency of t...