Abstract
A numerical method is proposed to calculate damping properties for mixed structure including elastic body, viscoelastic body and porous body using FEM. Displacement vectors as common unknown variable are solved under coupled condition. Besides, explicit expressions of modal loss factor for the mixed structures are derived using asymptotic method. Using this technique, eigenvalue analysis and frequency response analysis are performed for some automotive body panels with multi-layered sound proof structure. Vibration isolation characteristics of triple walls with sound absorbing material are compared with those of double walls with sound absorbing material.
