奈米流體阻尼器研發

Development of Nano-Fluid Viscous damper

彭聖凱(Shen-Kai Peng)

指導教授 ： 張國鎮

國立臺灣大學/工學院/土木工程學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201703942

摘要

鑒於台灣位處環太平洋地震帶上，地震發生次數相當頻繁，現有結構除需考量地震危害加以設計外，更應兼顧結構於地震後受損的修復，以確保維持使用功能。近年來隨著科技的發展，以結構韌性換取耐震能力的作法，不再是唯一抵禦地震的設計方法，被動或半主動的隔減震技術相繼成熟，儼然成為新一代的耐震主流。液態黏性阻尼器做為被動減震消能元件，已被廣泛應用於建築物、橋梁、或是結構體之興建與補強，然而市面上的阻尼器皆透過其內部之物理機構以控制力學行為，不但於研發階段需進行高成本製作與修改，更無法達到依使用需求而進行製作之目的，故工程師於應用階段將受到固定之阻尼器型號所限。
本研究目標為研發智慧型奈米流體阻尼器，透過設計阻尼器內部填充奈米流體之材料配比，以及調整簡單的物理機構(例如活塞頭長度或是內部環型間隙寬度)，即可以達到控制阻尼器力學公式F=CVα中，任意阻尼係數C 與非線性係數α之目的。其主要優勢有三，第一，阻尼器構造簡單，相對製作成本較為低廉，且阻尼器於研發階段中，不需製作大量的阻尼器試體來進行試驗與校正，僅需作內部填充奈米流體之更換，可節省大量的研發經費；第二，依據奈米流體黏度變化之特性，阻尼器將有雙α值，分別於小速度及大速度下為α>1及α<1之之力學模式，若設計得當將改善現有橋梁阻尼器受溫差與車行震動之油封損耗，甚或是使得隔震建築於中小度地震時隔震裝置有效發揮，而不至於受到阻尼器的抑制；第三，透過建立充分的奈米流體材料配比試驗資料庫，未來可輕易地製作出客製化阻尼器力學特性參數之奈米流體阻尼器，於應用層面而言，阻尼器可以配合工程師所提出之需求填充適當奈米流體，不但節省設計及製造成本，更可以有效提高結構設計之精準度及安全性。
本研究所採用之阻尼器填充流體以聚丙二醇 (Poly Propylene Glycol, PPG) 為載液，二氧化矽奈米顆粒做為溶質，並以PPG的分子量、不同型號之二氧化矽粒子及流體重量百分濃度為操縱變因，配製出一系列的奈米流體。透過流變儀進行流變試驗，以獲取奈米流體黏度與剪應變率之關係，並建立數值模型以擬合試驗結果，透過統計回歸的方式進行參數分析。運用上述已掌握之奈米流體材料性質結合流體力學理論，進行推估奈米流體阻尼器於各種配比及物理機構下的力學行為。最後，設計且製作實體具有雙桿及環間隙之阻尼器，並更換填充以不同配比之奈米流體，透過一系列的阻尼器性能試驗，以驗證理論與數值模型的正確性。

關鍵字

非牛頓流體 ； 奈米流體 ； 流體力學 ； 流變學 ； 液態黏性阻尼器

並列摘要

Taiwan, located on Pacific Rim seismic belt, frequently experience earthquakes; hence structures need to be not only designed with the consideration of earthquake hazard, but also need to remain functional after earthquakes. Further developments of technology have shown that ductility design is no longer the only way to resist earthquakes. Passive or semi-active control systems have been developed and are being widely used. Viscous dampers are widely utilized in buildings, bridges and structures as a passive damping energy dissipating elements. However, the dampers on the market adjust their mechanical behaviors through altering physical geometry, which have high-cost production and modification in both the developmental and manufacturing phases. Furthermore, dampers cannot be customized, thus engineers will be limited by the fixed damper size during structural design.
This study is dedicated to the development of a passive-type nano-fluid viscous damper, which is a simple physical mechanism and only requires suitable compound ratio of the nano-fluids to achieve the purposes of controlling the damping coefficient C and non-linear coefficient α of the damper’s mechanical formula: F = CVα. Nano-fluid viscous dampers have three main advantages: First, due to uncomplicated physical geometry, the production cost is relatively low. It is also needless to produce new dampers for calibration after testing, just to replace the internal filling of the nano-fluid, which may save on considerable R & D funding. Second, according to the characteristics of variability viscosity of the nano-fluid, nano-fluid viscous dampers are dual-α value damper, matching α>1 and α<1 performance under small and large velocity respectively. If designed properly, the damper may ameliorate the existing bridge damper oil seal wear caused by daily temperature difference and vehicle vibration. Furthermore, the damper enhances isolation system performance during small earthquakes. Last, through the establishment of a full range nano-fluid database, the manufacturer can produce customized dampers in the future, and consequently meet the engineers’ design, which can improve the accuracy and security of the structure.
In this research, the fluid solvent and solute filling in nano-fluid viscous dampers are poly propylene glycol (PPG) and silica nanoparticles. The independent variables of the nano-fluid are PPG molecular weight, different types of silica particles, and fluid concentration due to rheology testing. The numerical model was established to fit the test results, and further analysis of the parameters were gathered from nonlinear regression. We deduced the mechanical behavior of the nano-fluid viscous damper based on the material properties of nano-fluid and fluid dynamics theories. Finally, a damper with a double rod and annular gap were designed and manufactured. Afterwards, we verified the correctness of the theoretical and numerical models through a series of damper performance test with different nano-fluids.

並列關鍵字

Non-Newtonian fluid ； Nano-fluid ； Rheology ； Viscous Damper

參考文獻

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