AN INTEGRATED MODEL OF SCATTERING FROM AN IMPERFECT INTERFACE

The antiplane shear, SH or scalar problem of scattering from an interf ace characterized by a narrow region of heterogeneity is considered. A n approximate integral representation of the scattered wave fields in terms of a Green's function for a reference problem, and the stress an d momentum polarizations averaged through the thickness of the interfa ce is derived. Providing certain material contrast parameters are O(1) , the error in this expression is formally O(kh)(2), where k is the wa ve number and 2h is the thickness of the interface. To find the unknow n polarizations we specialize to a model configuration that is periodi c over a length scale much greater than the characteristic length scal es of the heterogenities in the interface. This allows an exact formul ation in terms of an infinite system of algebraic equations. Expressio ns modeling the reflection and transmission measured by a coaxial, con focal pair of transducers are then derived so that the effects of the transducer can be included in the modeling. These coefficients are cal culated in terms of the solution of the algebraic system. Numerical re sults for several different model interfaces are presented. (C) 1996 A coustical Society of America.