Theoretical and numerical modeling of ultrasonic scattering in polycrystalline materials

The strong interaction between the polycrystalline microstructure and elastic waves makes it challenging to fully understand and master the relationship between ultrasonic grain scattering and the crystallographic and morphological characteristics of the microstructure, which is nonetheless of paramount importance for the success of ultrasonic non-destructive testing of polycrystalline materials. In this seminar, I will present the theoretical and numerical models developed to investigate the effects of microstructural properties – such as grain size distribution, grain shape, and preferred crystallographic orientation – on scattering-induced attenuation, wave velocity variation, and the backscattering coefficient. Regarding coherent wavefronts, the theoretical study is conducted within the frameworks of two well-known seminal models: Stanke and Kino’s unified theory and Weaver’s model. Structural noise due to incoherent waves is studied using an approach based on the reciprocity theorem. For the numerical study, grain-scale finite element modeling is presented, along with the development of a space discontinuous Galerkin finite element solver.