Frequency Dependence of Acoustoelastic and Acoustoplastic Effects.

Abstract

Ulrrasonic wave velocities propagating in a plastically deformed medium are known to be dependent upon its microstructural properties (e.g., crystallinestructure, distributions of micro cracks, residual stresses and texture, etc). The authors have proposed the theoretical modeling for an ultrasonic nondestructive evaluation method of the microstructural property of the materials under the plastic deformation. Generally, wave propagating characteristics are also dependent upon the propagating wave frequency. hence to accomplish a precise evaluation of material property changes it is necessary to examine an influence of frequency dependence on the propagating wave veloclties. In the present paper, frequency dependence of acoustoelastic and acoustoplastic effects, which correspond to wave velocity changes due to the stress and material property changes. respectively, are studied experimentally on the longitudinal and Rayleigh surface waves and also are simulated using our proposed theory via Granato Lucke's model for dislocation damping.