Development of New Sound Insulation Simulation Technology Using Finite Element Method for Efficiency of High Aspect Ratio Core in Low Frequency Range

Abstract

Nowadays, meta-materials are being studied to reduce vehicle interior noise. But it has not yet been found effective meta-materials at low frequencies below 500Hz. A panel with one core which has an excellent sound insulation where the higher the height of the core, the better the sound insulation characteristics have been founded. And so, depending on the core height, a structure with one core which is effective even at 500hz or less may be obtained. If the core height is high, it cannot be obtained by press forming, so the origami forming has been developed. Use of FEM which is versatile for shape of structure is effective for analysis of the plate with core or with sound absorbing material. Although the FEM analysis for sound insulation analysis was difficult, so far, two methods have been developed. Here these two methods to a flat plate and a flat plate with sound absorbing material to grasp their characteristics are compared and applied. And then the more versatile method is selected for sound insulation analysis to plates with one core which are formed by origami forming. As a result, it is shown that a plate with one core is effective for sound insulation characteristics at the low frequency below 500Hz depending on the balance between plate thickness and core height. At last, it is shown the core shape that maximizes the integral value of the sound insulation characteristic from 0 Hz to 500 Hz by an optimal analysis.