Analysis of Dissipated Energy Using Vibration Intensity.

Noise of panel-composed structures is mainly caused by panel vibration with atmosphere-pressure fluctuation. In order to reduce noise, a large quantity of damping material has been pasted on panels. In vibration intensity (VI) analysis, the flow of vibration energy (power) is expressed by vectors, showing the energy propagation routes on panels at a certain mode of vibration during forced vibration. This paper shows the calculation of dissipated vibration energy from VI values and clarifies the relationship between damping material and vibration reduction. First, this paper shows that results of the measurement by the cross spectrum technique correspond with results of calcula-tion using the finite-element method (FEM), and that quantitative analysis of dissipated energy is possible using VI on a two-dimensional structure composed of a panel and frames. Second, VI is analyzed on a three-dimensional structure composed of panels and frames, using FEM in consideration of internal forces for applicaion to real structures. The distribution of dissipated energy is calculated from the results of VI analysis of panels, and the effect of damping material pasted on panels is clarified. The effect on vibration reduction is verified for damping material pasted on the area where much energy is dissipated on panels.