Semi-analytical modeling of ultrasonic fields in solids with internal anomalies immersed in a fluid

Modeling of ultrasonic fields in presence of cracks, inclusions and delaminations in materials is of great interest to the researchers in the field of real time non-destructive evaluation (NDE) and structural health monitoring (SHM). Ultrasonic fields generated by finite size transducers in various structures with cracks and inclusions simulating actual experiments have been studied by numerical and semi-analytical techniques. However, many of the semi-analytical techniques lack simple implementation for complex structure geometries and numerical techniques often suffer from accuracy problems at high frequencies. Several attempts to compute the ultrasonic fields inside solid media have been made based on approximate paraxial methods such as the classical ray-tracing and multi-Gaussian beam models. These approximate methods have several limitations. A new semi-analytical method is adopted in this paper to model elastic wave fields in half-space and plate structures with internal anomalies generated by finite size transducers. A general formulation good for both isotropic and anisotropic solids is presented in this paper. No simplifying assumption has been made on the geometry of the anomalies. Therefore, the formulation presented in this paper can be applied to anomalies with any geometry.