### ASA 127th Meeting M.I.T. 1994 June 6-10

## 3aPA5. A modified T-matrix approach for scatterers with mixed boundary
conditions or concavities.

**Vasundara V. Varadan
**

**
Yong Woo Kim
**

**
Vijay K. Varadan
**

**
**
*Res. Ctr. for the Eng. of Electron. and Acoust. Mater., Dept. of Eng. Sci.
and Mech., Penn State Univ., University Park, PA 16802
*

*
*
Many scattering problems involve specification of different types of
boundary conditions on different parts of the surface of the same scatterer or
the geometry of the scatterer may involve concavities. Both these problems are
difficult to model using available methods. The applications of such problems
are however many---debonded fibers in fiber reinforced composites, partially
coated inclusions in engineered coatings, to name just two. A modification of
the usual T-matrix approach is proposed by constructing a mathematical surface
which partially includes the actual surface of the scatterer. The integral
representations for the fields for the two regions---the actual scatterer
volume and the volume enclosed by the extended surface are simultaneously
solved. A general formulation is presented with numerical results for P- and
S-wave scattering by partially debonded fibers in an elastic matrix. [sup
a)]Present address: Samsung Electronics, Suwon, Korea.