Buzz-o-sonic use the Impulse Excitation Technique...
tap the sample
measure the vibrations
get the frequency (f)
Also known as impulse excitation of vibration, resonant vibration, impact acoustic resonance, eigen frequency method, or ping test, is where an elastic solid is tapped lightly with a small impulse tool causing the solid to vibrate at its natural frequencies. Although an elastic solid can vibrate in several modes simultaneously, the sample is supported and struck in such a way, that only one mode of vibration is prevalent. A typical example is shown below.
A screen shot from the Buzz-o-sonic main module is shown on the left.
The lower graph shows the amplitude of the vibrations plotted against time (waveform). Note the yellow curve fitted to the waveform envelope. This is used to calculate the internal friction (discussed below).
The upper graph shows the amplitude or power (amplitude squared) plotted against the frequency (frequency or power spectrum). The sample was struck and supported in such a way that a clean, single-peak spectrum was obtained.
Buzz-o-sonic has several settings to aid in obtaining a clean spectrum such as Window functions (Response shown in the example) and waveform time offset (73 ms shown on example).
The elastic constants can then be calculated from the dimensions and mass of the sample and from the frequency for a given mode of vibration.
Buzz-o-sonic has built-in algorithms based on ASTM standards E1876 and C1259, to calculate the elastic constants of bars, cylinders, and discs. We also provide methods for measuring other shapes such as grinding/cut-off wheels, annular plates, square plates, tubes, rings, and bone-shaped tensile bars. A Microsoft® Excel® Spreadsheet is also available. Contact us for more details.
Buzz-o-sonic, has been shown to be very precise and reproducible by E. Lara-Curzio, M. Radovic, and L. Riester at Oak Ridge High Temperature Materials Laboratory. On comparing the impulse excitation technique (IE) to some other techniques, it was found that IE gave superior precision and repeatability to nanoindentation and four-point bending. The results were published in Materials Science and Engineering, A368 56-70 (2004).
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