Vibration Power Flow Analysis in Structure Using FEM

Abstract

The analysis method of the structure-borne sound on the steel or aluminum structure like a ship is examined at low frequencies. Statistical energy analysis (SEA) is a good way of predicting the spatially averaged velocities of structures at high frequencies. It is, however, not good for SEA to identify specific power flow paths through a structure or to estmate spatial variations of power flow in the substructures at low frequencies. In this paper, the finite element method (FEM) is used to calculate the vibrational power flow of simple plate models and an actual ship structure. MSC/NASTRAN, which is a widely used program for structural dynamics, is applied to calculate the velocities at grid points and the forces on elements of a structure. Then these NASTRAN output are transformed the vibrational power flow of a structure. First, the application of a FEM model to the power flow calculation is discussed. Both beam elements and plate elements are considered as structual elements. Next, a simple plate model is analyzed to verify the power flow distribution on a substructure and to predict the influence of the damping treatment upon the power flow. Finally, it is shown that this method can be applied to predicting the input power from a noise source like a main engine to the hull structure of a high speed ship.