A more stable scheme for BEM/FEM coupling applied to two-dimensional elastodynamics

A linear theta method is used in this paper in order to improve the stabili ty of the time domain BEM/FEM coupling formulation. To make possible the co upling of BEM approaches that employ the standard linear theta method with FEM algorithms that employ the Newmark scheme, the former has to be modifie d. In the standard linear theta method, the response is initially computed at the time (n + theta)Deltat and subsequently the response at the time (n + 1)Deltat is obtained. In the modified version, integral equations are wri tten at the time (n + theta)Deltat and then modified so that unknowns at th e time (n + 1)Deltat are introduced back in the BEM system of equations. Th us it becomes possible to write BEM/FEM coupling compatibility conditions a t the time (n + 1)Deltat. In this way, the theta scheme, which is more stab le than the standard BEM formulation, is implicitly considered. The stabili ty improvement achieved by the formulation presented here, when applied to two-dimensional elastodynamics, is illustrated by two numerical examples. T he effect of varying theta on the stability of the numerical responses is a lso studied in this paper. (C) 2001 Elsevier Science Ltd. All rights reserv ed.