ISSN: 0149-6115
Published Online: 5 October 2009
Page Count: 16

New Methodology for Source Characterization in Pulse Velocity Testing

Tallavó, Fernando
Research Assistant,Civil and Environmental Engineering Dept., Univ. of Waterloo,ON,

Cascante, Giovanni
Associate Professor,Civil and Environmental Engineering Dept., Univ. of Waterloo,ON,

Pandey, Mahesh D.
Professor,Civil and Environmental Engineering Dept., Univ. of Waterloo,ON,

(Received 7 February 2008; accepted 17 August 2009)

Abstract

The pulse velocity test (PVT) is an ASTM standard for the measurement of compressional wave velocities in geomaterials. The PVT is based only on the first arrival of the wave. Full-waveform analysis can be used to measure the variation in geomaterial properties with frequency but requires the dynamic characteristics of the transducers. This paper presents a new methodology for the dynamic characterization of ultrasonic transmitters based on experimental and numerical results. Different types of excitation pulses (input signals) are used, and their theoretical Fourier spectra are computed. The methodology is demonstrated using a piezoelectric accelerometer to measure the frequency response function of an ultrasonic transmitter (UT) (50 kHz). The complex exponential method is used to extract the dynamic properties of the transmitter from transient time signals. Experimental results show that this methodology can be used for the dynamic characterization of ultrasonic transmitters. Results from finite element numerical simulations of wave propagation agree with laboratory results.

Keywords:
ultrasonic transmitters, electrical pulses, complex exponential method, Fourier series coefficients, power spectrum

Paper ID: GTJ101689
DOI: 10.1520/GTJ101689
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