Three-dimensional waves in layered media with nonparallel and curved interfaces: A theoretical approach

A calculation method is presented for transducer-generated three-dimensional, transient wave fields in layered media with curved interfaces by using a separation approach in combination with integral transform methods and point source synthesis. The transducer-specimen module is decomposed into different layers and the wave propagation is calculated separately in each layer. To simplify the boundary conditions, the existence of a thin liquid layer between two solid media is used. Using generalized ray theory it can be shown that the normal stress on the interface caused by an incident wave provides sufficient information to calculate the transmitted waves in the adjacent media. Two different functions for the point sources of the exciting element and the source function for normal stress are derived. By means of a source function for normal stress, the transmitted transient wave can be determined from the normal-stress distribution on the interface. The method is demonstrated by two examples. (C) 1996 Acoustical Society of America.