Basic development of a hybrid finite element method for mid‐frequency computations of structural vibrations

In the past it has been demonstrated that energy finite element analysis (EFEA) allows computation of high‐frequency structural vibration in complex marine structures and produces results similar to statistical energy analysis (SEA) predictions [Vlahopoulos et al., ‘‘Numerical implementation, validation, and marine applications of an energy finite element formulation,’’ accepted by the Journal of Ship Research]. In this paper a basic theoretical development of a hybrid finite element method is presented. Conventional finite element analysis (FEA) is combined with EFEA in order to achieve solution to mid‐frequency vibrations. The new formulation is based on deriving appropriate interface conditions at the joints between members modeled by the FEA and the EFEA methods. Effects of strong coupling, power re‐radiation, and power re‐injection can be accounted in the analysis. Examples of systems of co‐linear beams will be presented. Analytical solutions are compared to the hybrid solution in order to validate the theoretical developments. [Research supported by Automated Analysis Corporation.]