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Vibration analysis of an isotropic elastic-sphere oscillator contacting a semi-infinite cubic solid is investigated by considering dynamic deformation at the contact interface. Assuming sufficiently small oscillation amplitude of the sphere compared with the static indentation deformation, the dynamic maximum contact pressure and the variable contact radius yield a dynamic-contact pressure distribution of constant contact radius. The combination of the sphere oscillation and the solid motion at the contact interface through contact-displacement conditions gives resonance frequencies of the elastic sphere. Unlike the conventional quasi-static model, this dynamic contact model agrees well with the measurements, which will benefit the quantitative evaluation of the local Young's modulus and the orientation of micro-scaled anisotropic grains by the resonance-frequency shifts of a vibrating oscillator in resonance ultrasound microscopy and the efficient removal of micron or sub-micron particles from the substrate in the dry laser cleaning technique. [ABSTRACT FROM AUTHOR]

Resonant-ultrasound microscopy with a free-standing 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-6A1-4V composite to visualize its elastic-stiffness distribution. [ABSTRACT FROM AUTHOR]