A unified boundary element method for the analysis of sound and shell-like structure interactions. II. Efficient solution techniques

Efficient solution methods are investigated in this paper for solving the linear system of equations resulting from the recently developed boundary element method ~BEM! for the coupled structural acoustic analysis @S. H. Chen and Y. J. Liu, J. Acoust. Soc. Am. 106, Pt. 1, 1247–1254 ~1999!#. An iterative solver, namely, the quasiminimal residual method ~QMR!, is selected among others and found to be very favorable over the direct solver for solving the linear systems of equations with complex coefficients generated by the structural acoustic BEM. Four problem-dependent preconditioning schemes are developed to facilitate or accelerate the convergence of the iterative solver. A new effective preconditioner specially designed for frequency-sweep analysis is also presented in this paper. With this preconditioner, the iterative solver has been found to be stable in a frequency-sweep analysis and can converge much faster than the direct solver. The double-precision arithmetic is also found very useful in improving the convergence rate of the iterative solver for structural acoustic problems. © 2000 Acoustical Society of America. @S0001-4966~00!04512-4#