Transducer beam field modeling in anisotropic media by superposition of Gaussian base functions

Anisotropic structural materials like fiber composites, but also columnar-grained stainless steels raise considerable problems for ultrasonic inspection due to the well-known wave propagation phenomena of skewing, splitting and distortion. In this respect, simulation and optimization in ultrasonic testing have gained a considerable importance. Among a variety of methods for transducer field calculation, beam superposition has proven to be highly efficient. In this contribution, a Gaussian beam approach for anisotropic media is presented. The Gaussian base functions are obtained from relationships previously derived for Gaussian wave packets in general transversely isotropic media. Each function is furnished with coefficients fixing the beam waists and their position. To test the approach, the case of a piston radiator is addressed. As a reference, the Generalized Point-Source-Synthesis method (GPSS) is applied. The reduction of computer run-time compared to GPSS is enormous: at a frequency of 10 MHz, run-time is reduced by a factor of more than 10³