Accuracy of resonant ultrasound spectroscopy: an experimental study

We use resonant ultrasound spectroscopy (RUS) to routinely determine elastic-stiffness coefficients. To establish the uncertainty of RUS, we determined the longitudinal wave velocity in a cylinder (25.6 mm×25.4 mm diam.) of fused silica using three different ultrasonic time-of-flight measurement geometries and four different signal-analysis techniques. We carried out these measurements from 1 MHz to 20 MHz with usable bandwidths of at least 80% of the center frequency. Also, our short-pulse analyses accounted for diffraction, temperature differences, and pulse shape. From these measurements we determined the “true” velocity to be 5932.3 m/s ±0.13% with a 95% confidence interval. We used the RUS technique on the same specimen, operating from 60 kHz to 300 kHz. The RUS result is 5934.5 m/s, which differs from this “true” velocity by 0.04%. Our study shows that the RUS technique has an accuracy that is at least comparable to our best laboratory time-of-flight methods