Automatic coupling of a boundary element code with a commercial finite element system

An automatic procedure for the coupling of a linear elastic three dimensional boundary element code with a commercial finite element system is presented. Each closed BE domain in the mixed FEM/BEM model is defined as a finite macro element for which a stiffness formulation is generated by the 3D Symmetric Galerkin Boundary Element Method (SGBEM) and hence can be assembled to the global finite element formulation. For the case of combining finite shell elements with 3D boundary elements coupling equations in an integral sense are implemented as user defined multi point constraints. No user interaction is required during the analysis since detection of the coupling configurations, setting up and applying the MPCs is realized in an automatic manner. An in-house SGBEM code is used in combination with the commercial finite element package ABAQUS for automatically coupled FEM/BEM-analyses. Basic steps of the automatic coupling procedure are explained and necessary background information is provided. Some examples and illustrations display the capabilities of the developed software and a comparison of the combined FEM/BEM technique with pure SGBEM and FEM simulations underlines its benefits.