Ultrasonic damping in polycrystalline materials

Boström, Anders; Chalmers University of Technology; Sweden

Boström, A.E.; Chalmers University of Technology; Sweden

ID: ECNDT-0154-2018
Download: PDF
Session: Microstructural Scattering - UT 1
Room: J2
Date: 2018-06-13
Time: 09:20 - 09:40

Ultrasonic damping in polycrystalline materials

Anders Boström
Chalmers University of Technology
Department of mechanics and maritime sciences
Gothenburg, Sweden
Email: anders.bostrom@chalmers.se

The grains in a polycrystalline material, typically a metal, act as scatterers of ultrasonic waves and thus give rise to attenuation of the waves. The grains have anisotropic stiffness properties, typically orthotropic or cubic. A new approach is proposed to calculate the damping in a 2D setting starting from the scattering by an anisotropic circle in an isotropic surrounding. This problem has recently been solved giving explicit, simple expressions for the elements of the transition (T) matrix (which gives the relation between the incoming and scattered fields) when the circle is small compared to the ultrasonic wavelengths. The T matrix is used to calculate the total scattering cross section, which in turn can be used to estimate the damping in the material. Completely explicit expressions for the damping coefficient for longitudinal and transverse waves are obtained in this way.