Index of content:
Volume 111, Issue 4, April 2002
- ACOUSTICAL MEASUREMENTS AND INSTRUMENTATION 
111(2002); http://dx.doi.org/10.1121/1.1459465View Description Hide Description
Acoustical and dynamic mechanical measurements were carried out on a commercial polyurethane rubber, DeSoto PR1547. The sound speed and attenuation were measured over the range from 12.5 to 75 kHz and 3.9 to 33.6 °C. Shear modulus was measured from to 2 Hz and −36 to 34 °C. The peak heights of the shear loss tangent varied with temperature, demonstrating thermorheological complexity. At higher temperatures, time–temperature superpositioning could be applied, with the shift factors following the Williams–Landel–Ferry equation. From the combined acoustical and mechanical measurements, values for the dynamic bulk modulus were determined. Moreover, superposition of the bulk modulus data was achieved using the shift factors determined from the dynamic mechanical shear measurements. Finally, this work illustrates the capability and the working rules of acoustical measurements in a small tank.
111(2002); http://dx.doi.org/10.1121/1.1459464View Description Hide Description
A sensitive radiation force balance for laboratory measurement of ultrasonic power is presented. The principle of the system is based on measuring the ultrasonic radiation force exerted on a conical float suspended in water. Technical details of the implementation of the economically attractive system are described. The operation of the system is automated with the aid of the IEEE-488 bus and a desktop computer. Design aspects that affect measurement uncertainty are investigated. A theoretical model for the measurement of ultrasonic power with a conical reflector target is discussed. The expanded uncertainty (95% confidence level) of the above radiation force conical float system is estimated to be between 5% to 10%.