Numerical analysis of longitudinal ultrasonic attenuation in sintered materials using a simplified two-phase model

Techniques of quantitative nondestructive evaluation using attenuation of ultrasonic waves have been proposed as a potential tool for monitoring sintering processes because of the direct connection between the changes of wave propagation characteristics and microstructure properties. However, the influence of these changes during sintering on sound propagation remains unclear. In addition to theoretical investigations, numerical models can be utilized to provide key information for interpreting experimental data quantitatively. In this article, a simplified two-phase model using Voronoi polycrystals is applied to study wave propagation through sintered materials. Finite element simulations are developed with various material and geometric parameters of the two-phase model. Example longitudinal attenuation results are obtained and compared with the scattering theory for different input wave frequencies. The comparison of the numerical results with the theory shows the dependence of the attenuation on the parameters of the correlation function and the two-phase geometry. The results also validate the correlation function formula used in the theory. The influence of the input wave frequency and material properties on the correlation lengths is also discussed. Such numerical models can be used to verify theoretical models efficiently and to design further experimental methods for characterization of microstructures.