Calculation of wideband ultrasonic fields radiated by water-coupled transducers into heterogeneous and anisotropic media

Ultrasonic nondestructive testing may be operated on pieces of complex structure, such as welded components in nuclear plants. Crystallographic analyses of these structures display both anisotropic and heterogeneous characteristics, so that the material may be modeled as a succession of anisotropic media separated with interfaces of arbitrary shape. The aim of this paper is to describe the extension of the model Champ-Sons developed at the French Atomic Energy Commission to predict transient fields radiated from arbitrarily shaped sources into such pieces, for which numerical efficiency is required. This model is based on two models that have been presented at 1997 and 1998 QNDE conferences. A pencil description is used. Each pencil propagating from an elementary source on the transducer to a calculation point into the solid and following a geometrical path is described by means of a 4×4 matrix, which is the product of elementary ones, describing either the propagation into a homogeneous medium or the tra...