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


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