Abstract:

The use of resonant free--free bars to determine the elastic properties of materials has been presented previously [Garrett, ``Resonant acoustic determination of elastic moduli,'' J. Acoust. Soc. Am. 88, 210--221; Brown, ``Characterization of viscoelastic materials using the resonant modes of a `free--free' bar,'' J. Acoust. Soc. Am. 94, 2294(A) (1993)]. The preferred excitation and detection method is based on electrodynamic transduction in which a coil of wire is attached to each bar end, which in turn is subjected to a strong magnetic field. The effect of the added transducer mass on the observed resonant frequency and quality factors of longitudinally driven bars used to determine Young's modulus and damping will be reported. [Work supported by the University of Massachusetts Dartmouth.]