SUMMARYIn the past two decades, considerable improvements concerning integration algorithms and solvers involved in boundary-element formulations have been obtained. First, a great deal of efficient techniques for evaluating singular and quasi-singular boundary-element integrals have been, definitely, established, and second, iterative Krylov solvers have proven to be advantageous when compared to direct ones also including non-Hermitian matrices. The former fact has implied in CPU-time reduction during the assembling of the system of equations and the latter fact in its faster solution. In this paper, a triangle-polar-co-ordinate transformation and the Telles co-ordinate transformation, applied in previous works independently for evaluating singular and quasi-singular integrals, are combined to increase the efficiency of the integration algorithms, and so, to improve the performance of the matrixassembly routines. In addition, the Jacobi-preconditioned biconjugate gradient (J-BiCG) solver is used to develop a generic substructuring boundary-element algorithm. In this way, it is not only the system solution accelerated but also the computer memory optimized. Discontinuous boundary elements are implemented to simplify the coupling algorithm for a generic number of subregions. Several numerical experiments are carried out to show the performance of the computer code with regard to matrix assembly and the system solving. In the discussion of results, expressed in terms of accuracy and CPU time, advantages and potential applications of the BE code developed are highlighted.

SUMMARYEfficient integration algorithms and solvers specially devised for boundary-element procedures have been established over the last two decades. A good deal of quadrature techniques for singular and quasisingular boundary-element integrals have been developed and reliable Krylov solvers have proven to be advantageous when compared to direct ones, also in case of non-Hermitian matrices. The former has implied in CPU-time reduction during the assembling of the system of equations and the latter in its faster solution. Here, a triangular polar co-ordinate transformation and the Telles co-ordinate transformation are employed separately and combined to develop the matrix-assembly routines (integration routines). In addition, the Jacobi-preconditioned Biconjugate Gradient solver (J-BiCG) is used along with a generic substructuring boundary element algorithm. Thus, solution CPU time and computer memory can be considerably reduced. Discontinuous boundary elements are also included to simplify the coupling of the BE models (substructures). Numerical experiments involving 3D thin-walled domains (shell-like structural elements) are carried out to show the performance of the computer code with respect to accuracy and efficiency of the system solution. Precision, CPU-time and potential applications of the BE code developed are commented upon.