極正交環板之可調式阻尼與自然振動頻率之特性分析

A Tunable Damping and Natural-Frequency-Characteristic Analysis of an Orthotropic Annular Plate

本文主要在於推導並建立三明治極正交環板系統的運動方程式與分析模型的建立。採用分析力學（analytical mechanics）的方式來推導系統的運動方程式並利用離散層有限元素法（discrete layer finite element method）來分析系統的振動特性與阻尼變化。在本文中討論了含電變流體之三明治極正交環板系統的阻尼特性與自由振動，其中所使用的電變流體材料特性則利用複數的形式來加以描述。文中討論電變流體的厚度與施加的電場強度對於三明治極正交環板系統的特性影響，而系統的模態損失因子會隨著施加電場強度的改變而產生變化。因此，在此三明治極正交環板系統系統上貼覆此類主動式智能材料阻尼層除了可使系統更加的穩定外，也可達到主動控制的效果。 In this study, the equations of motion for a polar orthotropic annular sandwich plate are derived by using the discrete layer finite element method. The extensional and shear modulus of the electrorheological (ER) fluid layer are described by complex quantities; moreover, the tunable damping of the sandwich system is more effective when the electric fields are applied. The ER fluid core is found to have a significant effect on the vibrational behaviors of the plate. Finally, the effects of ER layer thickness, base annular plate stiffness, and certain designed parameters on natural frequencies and modal loss factors are also discussed.