Nonlinear acoustics and its impacts on nondestructive evaluation and acousto-optics

Abstract

Nonlinear acoustics have witnessed a tremendous amount of work in the last 40 years. Finite amplitude wave propagation lead to the evaluation of important material parameters, e.g. B/A for liquids and third order elastic constants for solid materials. These quantities are related to nonlinearity of materials. More recent works have utilized the concepts that material inhomogeneities which clearly reduce the strength of materials on the microscopic scale are insensitive to measurements of linear acoustic parameters e.g. velocity, attenuation, or reflection coeffecient etc., but quite sensitive to variation of nonlinearity parameters. Recent work on nonlinear acoustic measurement related to nondestructive evaluation problems and a newly developed acousto-optic technique to measure nonlinearity parameters will be discussed.