Damped Vibration Responses for Automotive Sound Proof Structures Using Three-Dimensional Finite Element Method : Effects of Connection Parts between Double Walls on Modal Damping(Mechanical Systems)

A numerical method is proposed to calculate damping properties for three-dimensional sound proof structure including elastic material, viscoelastic material and porous material. Displacement vectors as common unknown variable are solved under coupled condition. Further, explicit expressions of modal loss factor for the three-dimensional sound proof structures are derived using asymptotic method. Using this technique, eigenvalue analysis and frequency response analysis are performed for automotive double walls with a porous material. Further a spacer installed between a steel panel and sheet in the double walls to analyze deterioration of vibration.