質量球を粘弾性体に埋め込んだ制振デバイスの粘弾性特性の数値モデル構築に関する検討と多モード制振効果の実験的検証

Abstract

This paper describes the construction of the numerical model of a passive damping device called eMDVA (embedded Mass Dynamic Vibration Absorber) and experimental investigation of the eMDVA's multi-modal damping effect for elastic vibrations of a plate-like structure. The eMDVA consists of a ball-like mass embedded in a viscoelastic medium; and the mass can vibrate in every direction. When the thickness of the viscoelastic medium differs in the X, Y, and Z directions, the ball-like mass has different natural frequencies for every vibration direction. An appropriate numerical model that can predict these natural frequencies correctly is needed to design the eMDVA; in particular, defining the viscoelastic properties is an important and challenging subject. In this work, the Prony series is used to express the viscoelastic material, and the setting process of the coefficients in the Prony series is studied. It has been shown that using a sufficient number of terms in the Prony series and using sufficient measurement data to define their coefficient leads to good results in expressing the viscoelastic material. Using the constructed viscoelastic model, vibration characteristics of the eMDVA, such as the change of the natural frequencies versus the viscoelastic material's shape change and frequency response characteristics, are investigated numerically using a commercial finite element software Ansys. After that, an eMDVA is produced and applied to a plate-like elastic structure. A series of excitation tests are conducted, and the multi-mode vibration reduction effect by the eMDVA has been demonstrated.