Finite Element Analysis for Vibration Properties of Panels in Car Bodies Having Viscoelastic Damped Layer. 2nd Report. Influence of Geometry for Stiffened Panel on Model Damping.

Abstract

Viscoelastic damping materials are laminated on car body panels to reduce structure borne noise. In usual, these panels are stiffened by beads. Damping properties of the panels are sensitively affected by their complicated configurations. In the first report, we studied about prediction methods of damping properties for both bead panels and actual vehicle models having non-constraint viscoelastic layer. Applying asymototic method to the discreted equations of FEM, explicit expressions of modal loss factors for the laminates were derived, and then were verified by experiment. In this report, sensitive effects of geometry of beads (e.g. length of beads, height of beads and so on) on modal damping were revealed in detail. Applying Inoue's method, we also analized damping phenomena on the bead panels using distribution of dissipated energy between inplane deformation and out of plane deformation.