Predictions of the Gauss-Hermite beam model and finite element methodf or ultrasonic propagation through anisotropic...

The predictions of the Gauss-Hermite beam model are compared to those obtained by the finite-element method for a model problem. This is motivated by the desire to examine the trade-offs between computational speed and accuracy in the Gauss-Hermite model. In the model problem, a contact strip transducer radiates through an isotropic layer of ferritic steel into an anisotropic layer of austenitic stainless steel with various directions of the preferred axis of columnar grain alignment. Comparisons are made of time-domain waveforms in a common observation axis in the austenitic material. The predictions of the two models are found to be in good agreement near the center of the beam, with deviations developing as one moves away from the central ray. These are interpreted to be a consequence of the Fresnel approximation made in the Gauss-Hermite model. However, the region that contains most the energy is in the vicinity of the central ray, where there is excellent agreement between the two models. This loss in accuracy is accompanied by a several orders of magnitude increase in computation time.