Volume 115, Issue 2, February 2004
Index of content:
- ULTRASONICS, QUANTUM ACOUSTICS, AND PHYSICAL EFFECTS OF SOUND 
Vibration analysis on electromagnetic-resonance-ultrasound microscopy (ERUM) for determining localized elastic constants of solids115(2004); http://dx.doi.org/10.1121/1.1642618View Description Hide Description
In this paper we present a new acoustic-resonance microscopy, ElectromagneticResonance-Ultrasound Microscopy (ERUM), to measure the localized elastic stiffness of a solid material. It visualizes the resonance-frequency shift of vibrating piezoelectric crystal (langasite, excited by an electric field from a solenoid coil. The acoustic coupling is made only at the tip of the crystal touching the specimen surface. Being based on the calibration for the specimen’s effective stiffness, the local elasticity is determined from the resonance frequencies of the crystal with the Rayleigh–Ritz method. An approximate model for the specimen’s effective stiffness predicts the shift of resonance frequencies, for which the conventional Hertz-contact model is improved. As an illustrating example, the mapping of Young’s modulus of a duplex stainless steel is presented, which shows good agreement with the existing study.
Theoretical examination of ultrasonic pole figures via comparison with the results analyzed by finite element polycrystal model115(2004); http://dx.doi.org/10.1121/1.1642763View Description Hide Description
The ultrasonicwavevelocities in a polycrystalline aggregate are sensitively influenced by texture development due to plastic deformation. According to Sayer’s model, it is possible to construct ultrasonic pole figures via the crystallite orientation distribution function (CODF), which can be calculated by using ultrasonicwavevelocities. In the previous papers, the theoreticalmodeling to simulate ultrasonicwavevelocities propagating in solid materials under plastic deformation has been proposed by the authors and proved to be a good agreement with experimental results. Generally, wavevelocities are dependent upon the propagating wave frequency; hence to evaluate texture development via ultrasonic pole figures it is necessary to examine an influence of frequency dependence on the ultrasonicwavevelocities. In the present paper, the proposed theoreticalmodeling is applied to the texture characterization in polycrystalline aggregates of FCC metals under various plastic strain histories via ultrasonic pole figures, and also the frequency dependence is examined by using Granato–Lücke’s dislocation strings model. Then the simulated ultrasonic pole figures are compared with the pole figures analyzed by the finite elementpolycrystal model (FEPM). The good qualitative agreement between both results suggests the sufficient accuracy of our proposed theoreticalmodeling.