Nonlinear analysis of interacting saturated porous and elastic media by time-domain FEM/BEM iterative coupling procedures

This work deals with the coupling of the Finite Element Method (FEM) and the Boundary Element Method (BEM) to model interacting saturated porous and sealed elastic media. In this coupled analysis, the porodynamic sub-domains of the model are discretised by the FEM, and the elastodynamic interacting subdomains are discretised by the BEM. Nonlinearities may be considered within the FEM subdomains. An iterative coupling approach is adopted, which leads to an efficient and easy to implement formulation, enabling the FEM and BEM modules to be handled separately. The iterative coupling methodology allows nonlinear analyses to be carried out quite directly, considering a single iterative loop for all iterative computations. It also permits independent discretisations to be straightforwardly applied for each subdomain of the model, taking into account simple interpolation/extrapolation procedures on common interfaces. Optimal relaxation parameters are considered to speed up the convergence of the iterative coupling analysis. At the end of the manuscript, numerical examples are presented, illustrating the performance of the proposed formulation.