智慧型材料應用於黏性阻尼器之可行性研究－剪切增稠流體

Abstract

本論文主要研究之目的在於,將新式智慧型剪切增稠流體,應用於傳統的黏性阻尼器,並且自材料試驗以及理論推討之結果,研究此新式阻尼器應用於結構物被動控制上之可行性。 剪變增稠流體的特性為:當流體受到一剪切應力時,其黏滯度會在低剪應變率(或是流體截面之速度梯度)時隨著剪應力之增增加而迅速的抬升,而當流體超過某一臨界剪應變率後,黏滯度又會隨著剪應力增大而逐漸變小,最後則黏滯度則會維持在一定值上呈牛頓流體的型態。若將此種流體之特性應用於構造簡單的流動型(Flow Mode)阻尼器當中,則可以產生非線性且α值小於1之阻尼器出力效果(F = CVα);而α值小於1的黏性阻尼器亦有許多研究證明其消能之效果與經濟性優於α值等於1或是大於1的阻尼器。故若可以只利用改變流體黏滯度的方式,即可設計出不同C值與α值之黏性阻尼器,再加上由於其行為簡單且易於定性分析及評估,在設計工作上,優於傳統上利用改變機械性質的方法來設計之黏性阻尼器。 本論文所採用之材料為聚乙烯乙二醇(PPG)和粒徑為12奈米的二氧化矽微粒(12nm Fumed Silica Particle),其材料取得容易,成本較傳統黏性阻尼器所使用之矽油低。另一方面,流體的製作程序亦非常簡單,僅需充分的混和此兩種材料即可,且其成品不具有揮發性、對於溫度之敏感性極低,非常適合填充於阻尼器中,供結構物消能所使用。 本論文將流體的行為理論和阻尼器的運動機制結合,推導出由STF流體所填充之黏性阻尼器的理論行為模式,並證明其遲滯迴圈及阻尼器出力與速度之關係皆類似α值小於1之黏性阻尼器。另外,論文中亦有對於STF流體之實際製作與測試,其結果也符合流體特性。

The study focus on theoretical analysis of the behavior of viscous damper utilizing smart material, which is so called Shear Thickening Fluid. By the result of material testing and theory derivation, study the feasibility of installing this kind of new type viscous dampers into real structures. The viscosity behavior of the shear thickening fluid is that, while the fluid is under low shear rate range, the viscosity will rise steeply with shear rate; while the fluid is under middle shear rate range, the viscosity will decrease slowly; and in the end, while the fluid is under much higher shear rate range, the viscosity will maintains in a stable value and behaves like a Newtonian fluid. Fill the Shear Thickening Fluid into simply flow mode damper, so that the damper could behaves like the traditional viscous damper with α<1 (F = CVα), which has been proved have much more ability to dissipate energy from earthquake then other viscous dampers with α≧1. The advantages of Shear Thickening Fluid filled dampers are that the design method is only to change the thickness of fluid and size of dampers. It is much more convenience than traditional viscous dampers. The study use 12nm fumed silica particles and Polypropylene Glycol (PPG) to produce Shear Thickening Fluid. These two kind of material are easily to obtain and have low cost. The produce process is very simple. The only thing need to do is to mix these two materials together and stir sufficiently. The advantage of this fluid is that it has low sensitivity to temperature. This advantage makes the Shear Thickening Fluid suitable to work in the dampers. The study combined the theory of fluid and the mechanism of dampers, and furthermore derived out the behavior of Shear Thickening Fluid filled dampers, and proved that both of the relation between damper force and velocity and hysteresis loop are very like the behavior of traditional viscous dampers with α<1. On the other hand, the experiment presented in this study showed that the Shear Thickening Fluid is easily to produce and the properties of behavior is quite reasonable.