ABSTRACT Resonant-ultrasound microscopy with a freestanding rod oscillator has been developed for mapping a material's elastic properties in a localized surface region, for the purpose of evaluating elastic stiffness through the resonance frequency of the oscillator contacting the specimen by its tip. A stronger biasing static magnetic field makes the ferritic steel oscillator plumb without any other mechanical support except tip-sample contact. For a noncontacting acoustical coupling, the longitudinal vibration of the oscillator is excited and detected with a surrounding solenoid coil by the magnetostrictive effect. This freestanding configuration realizes only a mechanical ``point'' contact between the oscillator and the sample surface, which yields accurate measurement of the local elastic stiffness. As an illustrated example, the new microscopy method is applied to an SCS-6 SiCf/Ti-6Al-4V composite to visualize its elastic-stiffness distribution.
Digital Object Identifier 10.1109/TUFFC.2008.668
© 2008, by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.