抄録
We introduce a technique for estimating damped analysis of automotive body panels with sound insulation structure. It calculates damping properties for sound-proof structures involving panel (elastic body), resin sheet (viscoelastic body) and felt (porous media). For elastic and viscoelastic body displacement are modeled using conventional finite elements using complex modulus of volume elasticity. In the porous media, both effective density and volume elasticity have complex module to represent damped sound fields. Particle displacement in the porous media is discretized using finite element method. Displacement vectors as common unknown variables are solved under coupled condition between elastic body, viscoelastic body and porous media and gas. Further, explicit expressions of modal loss factor for the mixed structures are derived using asymptotic method. Using this technique, eigenvalue analysis and frequency responded were calculated for some automotive body panels with sound Insulation structure. We showed that phenomena of sound insulation changed greatly with panel shape.
