Index of content:
Volume 104, Issue 3, September 1998
- TRANSDUCTION 
104(1998); http://dx.doi.org/10.1121/1.424350View Description Hide Description
This paper presents a unique embeddible acoustic emissionsensor. Comparison with theoretically calculated waveforms for the embedded sensor, surface step force Lamb’s problem prove the sensor to be an accurate transducer of particle velocity, with sensitivity of 2.34 V output per mm/s. Calibration as a surface sensor by the National Institute of Standards and Technology (NIST) show the sensor to be an accurate transducer of surface displacement with a sensitivity of 2.8 V/nm. The paper presents details about the design and construction of the sensor as well as calibration and verification. Unique design elements include the use of a lead-alloy backing masses, soft elastomer shear-spring isolation and mounting, and embedment. The sensor is based on the NIST conical lead zirconate-titanate (PZT) element and has a finished length of 38 mm and a diameter of 16 mm. The sensor is robust enough to work under 1 MPa of brine pressure.
104(1998); http://dx.doi.org/10.1121/1.424351View Description Hide Description
This paper investigates an ultrasonicdensitometer capable of measuring the densities of liquids. Lynnworth originally proposed an ultrasonicdensitometer operating in pulse-echo mode. This instrument makes use of the phase velocity of a torsional elastic wave pulse traveling in a noncircular waveguide immersed in a liquid to indicate the density of the liquid under investigation. In this paper a second mode of operation is proposed by making use of a continuously excited torsional wave to reveal liquid density. An important advantage of this mode of operation is the larger cross-sectional dimensions possible without sacrificing performance degradation which might result from wave dispersion. The theory of this mode of operation is described and used to construct a densitometer. Densities of a few liquids are measured and compared to the theoretical values.