EMA 611, Lab 5--Resonant ultrasound spectroscopy (RUS)

Advanced Mechanical Testing of Materials

Engineering Mechanics Program, University of Wisconsin-Madison

Advanced Mechanical Testing of Materials

Engineering Mechanics Program, University of Wisconsin-Madison

Further links are at left of EMA 611 page.

Vibration mode structure of cubes, spheres, and compact cylinders. Determination of moduli. Determination of mechanical damping. We focus on isotropic materials for which the lowest mode frequency reveals the shear modulus, the resonance peak width reveals the mechanical damping, and frequencies of several higher modes reveal Poisson's ratio. Poisson's ratio is extracted by comparing frequencies from experiment with frequencies provided on graphs generated numerically. Frequencies are normalized to the fundamental frequency to allow comparison. This is a graphical approach.

RUS method pdf

tone bursts, sweeps, pdf

RUS diagram

setup image

Scope scan, PMMA 10-110 kHz

Scope scan Al alloy 50-150 kHz

Modes of isotropic cube, after Demarest

Modes of isotropic cube, full range of Poisson's ratio

Modes of isotropic sphere , after Yaoita et al.

Modes of isotropic cylinders, after Jaglinski et al.

Physics Today article by Julian Maynard pdf

Videos of vibration modes of isotropic cylinder with length equal diameter, after T. Jaglinski

torsion,

shear,

bend,

mixed bend,

flattening,

symmetric axial.

Software to interpret RUS scans is available here. Though it is not obvious, the assumed units for moduli are 10^12 dynes/cm^2. The software allows the user to invert RUS frequency scans to obtain anisotropic elastic moduli. Many modes are needed. The material needs to be of low damping so that the higher mode peaks are sufficiently sharp to distinguish them. Study of anisotropic crystals via RUS has a substantial learning curve and is beyond the scope of Lab 5 but it could be suitable for a project.