## 5aSA3. Generalization of analytical numerical matching for structural acoustic scattering with discontinuities using a composite Green's function approach.

### Session: Friday Morning, December 6

### Time: 9:00

**Author: Rickard C. Loftman**

**Location: Mech. Eng. and Mater. Sci., Duke Univ., P.O. Box 90300, Durham, NC 27708**

**Author: Donald B. Bliss**

**Location: Mech. Eng. and Mater. Sci., Duke Univ., P.O. Box 90300, Durham, NC 27708**

**Abstract:**

Analytical numerical matching (ANM), when applied to structural acoustics,
efficiently models structural discontinuities by superposing high-resolution
local analytical solutions at discontinuities upon a low-resolution global
numerical solution. This composite solution is very accurate and computationally
efficient. Previously, ANM composite solutions have been developed for several
specific problem geometries. A method for treating general constraint
configurations using ANM is presented using the Green's function concept, which
models general structural constraints as an integration of point force solutions
of the unconstrained structure. The general local solution is found by
integration of the ANM local solution derived in the case of a point force. The
point force local solution is analytic, known explicitly, and independent of
overall geometry. The complementary global solution is far smoother than the
original problem and, therefore, can be more efficiently calculated. In short, a
general discretely constrained problem is replaced by a smoothed constrained
problem, plus a local analytic correction. The method is demonstrated by
application to scattering from an infinitely long cylindrical shell with
periodic bulkheads. Accuracy and convergence of the structural response and
scattered pressure are compared using a classical modal solution, a previous ANM
modal solution, and the present general method. [Work supported by ONR.]

ASA 132nd meeting - Hawaii, December 1996