挫屈連桿樓板減振系統之初步研究

Abstract

科技廠房之樓板振動問題往往影響其生產良率，尤其是TFT-LCD廠因設備機台尺度遽增，多將廠房設計成大跨徑結構而導致樓板剛性不足，廠內自動搬運車之行止更造成樓板振動問題的惡化。儘管結構振動控制技術已趨成熟，但因樓板的振動幅度極小，習用之結構消能減震裝置並不適用。可變曲率勁度元件或稱挫屈連桿，由於其幾何非線性之結構特性，可在往復運動中產生遲滯消能行為，且在變形極小時即發揮消能作用，故被用於精密機台之減振，具備應用於廠房樓板振動控制之潛力。此外，挫屈連桿之彈性挫屈勁度隨變形而改變之特性，或有益於寬頻擾動源之減振。本研究旨在建立挫屈連桿之基本力學原理，並透過一系列的元件測試探討其遲滯消能行為。試驗結果顯示，挫屈連桿之受力-位移關係呈橢圓形之遲滯迴圈，類似黏滯阻尼器，其迴圈路徑穩定而飽滿，具備阻尼器之優異性能。本研究並根據試驗數據及系統識別技術，建立挫屈連桿之等效彈性挫屈勁度經驗公式，作為數值模擬預測之工具，以及後續應用挫屈連桿於廠房樓板減振分析之基礎。

The production quality of hi-tech industry is often adversely affected by floor vibration problems. For the TFT-LCD industry, in particular, with drastically increased large-scale fabrication tools, most fabs consist of frame structures of large spans, which leads to insufficient rigidity of the floor as a result. The motion/braking of AGV systems cause further degradation of floor vibration problems. Despite structural vibration control technology has become matured today, the existing seismic dampers are not applicable to floor vibration with scale in micro-vibration levels. Variable curvature stiffness device, or referred to as buckled strut, may dissipate energy in a cyclic loading process due to its essence of geometric nonlinearity. Being able to dissipate energy at extremely small deformations, the buckled strut therefore is adopted for vibration control of delicate fabrication tools, and considered of high potential in the application of floor vibration control. Moreover, the characteristic of displacement-dependent elastic buckling stiffness of the buckled strut makes it advantageous in the control of vibrations due to broadband disturbing resources. The purpose of this study is to develop basic principles of the buckled struts and explore their hysteretic behavior via a series of component tests. Experimental results indicate that the force-displacement relationship of buckled struts is in the form of ellipse, similar to that of viscous fluid damper. The hysteretic loops are stable and rich, indicating the buckled struts are qualified as dampers of excellent property. Based on the test data and system identification techniques, empirical formula of the equivalent elastic buckling stiffness of the buckled struts is derived for numerical prediction as well as the basis for analysis of fab floor vibration control using the buckled struts.