Elastic-stiffness mapping by resonance-ultrasound microscopy with isolated piezoelectric oscillator

A resonance-ultrasound microscopy has been developed for mapping a material’s elastic constant in a localized surface region. It detects the effective elastic modulus through a resonance frequency of free vibrations of a solid probe touching the specimen via a small tungsten-carbide bearing. Langasite (La3Ga5SiO14) crystal is used as a probe because of the low sensitivity of its elastic constants to temperature and its high piezoelectric coefficients. The vibration of the probe is excited and detected with a surrounding solenoid coil. This noncontacting acoustic coupling isolates the probe vibration and measures the resonance frequency with an accuracy better than one part in 105. This microscopic method is applied to a composite material consisting of silicon-carbide (SiC) fibers in titanium-alloy matrix. The stiffness distribution inside a single fiber was determined.Ogi H., Tian J., Tada T., et al. "Elastic-stiffness mapping by resonance-ultrasound microscopy with isolated piezoelectric oscillator", Applied Physics Letters, 83(3), 464 (2003) https://doi.org/10.1063/1.1593819