On the energy finite element method for the acoustic design of ships

Abstract

To ensure dynamic requirements of technical systems, methods like the finite element method (FEM) are successfully applied. For large structures as ship geometries, such analyses in the acoustic-relevant frequency range are usually not used productively. Highly time consuming investigations are incompatible to the generally single-unit production and short conception phases in ship design. The energy finite element method (EFEM) is a grid-based approach, which has the potential to provide a technique for the evaluation of acoustic characteristics even for major and complex structures at high frequencies. The less time consuming calculations generally result from a smaller number of degrees of freedom at the nodes and, in particular, it is feasible to use coarser grids than in the FEM. The governing equations are similar to that of the static heat conduction. State variables are the time and locally space averaged energy densities of the different wave types. The main focus is on the coupling— not only between the structure and the fluid, but also at junctions within the structure. Preliminary investigations on the reliability of EFEM results will be presented, questioning if the approach is applicable to operative ship design. [This work was done within the collaborative research project EPES.]