半主動同心螺旋流道式磁流變阻尼器之設計開發與特性研究

Abstract

磁流變阻尼器可在無磁場時以被動控制；在外加磁場的作用下，磁流變液由黏度較低的牛頓流體在幾毫秒內變為有高黏度與剪切強度的賓漢流體，隨磁場變化改變阻尼性能吸收結構震動能量。 本論文應用磁流變液體(Magnetorheological fluid，MR fluid)設計同心螺旋流道式磁流變阻尼器。同心螺旋流道的設計有在固定體積內增加流道的長度、使激磁後的磁流變液體流動方向與磁力線方面垂直等特性，且整合流道於阻尼器內具有體積小易安裝的優點。 使用MTS_810拉伸試驗機台測試磁流變阻尼器，測試項目包括位移、速度、阻尼力等。實驗結果顯示在0.25 Hz振幅1 mm的正弦波下，當輸入電流為0 A，阻尼力為304 N；電流為2.0 A時，阻尼力為1034 N，阻尼力動態係數(Dynamic ratio)為3.4 (1034/304)。因此，透過調節磁流變阻尼器的輸入電流就能達到半主動控制阻尼力的目的。 本論文利用數學分析軟體Matlab之分析模組Simulink建構Bouc-Wen磁流變阻尼器模型，再應用基因-模糊控制法作為控制輸入電流產生磁場變化來改變阻尼特性，將系統的位移、加速度和阻尼力作為訊號回饋，模擬一單自由度振動系統。由實驗結果可知磁流變阻尼器的半主動控制減振效果達47.5%。 同心螺旋流道式磁流變阻尼器具有高可調阻尼力範圍、結構緊緻且在無輸入電流狀態下也能產生基本的阻尼力，而且應用基因-模糊控制法驅動電流大小進而改變阻尼特性，可以有效的運用於結構半主動控制減振。

Magnetorheological dampers (MR dampers) are the fluid viscous dampers which use MR fluid as working fluid medium. The MR fluid can be transformed from low viscosity Newtonian fluid to Bingham fluid with higher viscosity and shear stress within only microseconds by applying external magnetic field. Thus, the damping characteristic of MR dampers can be effectively controlled to absorb the impact or vibration energy. In this thesis, a semi-active concentric spiral-flow magnetorheological damper (CSF damper) has been developed with the concentric spiral-flow channel. The spiral channel structure can keep the direction of magnetic field and flow perpendicular, and reduce the total size of CSF damper. The performance test of CSF damper was measured and conducted by using the MTS_810 tensile machine. The damper has been driven by sine wave movements with specific frequencies and amplitudes. By the result, the damping force is 304 N with the input frequency of 0.25 Hz and amplitude of ±1 mm without applied magnetic field, and reaches its maximum value as 1034 N with 2.0 A as the current to the coil for the applied magnetic field. The dynamic ratio of developed CSF damper is 3.4 (1034/304). Therefore, the semi-active vibration controlling effect can be easily regulated by the modulating of input current. The CSF damper is modeled based on the Bouc-Wen hysteresis model with MATLAB and Simulink. Furthermore, GA-Fuzzy control method has been adopted where the damping coefficient of CSF damper is controlled by regulating magnetic field. The result shows that the SDOF system can effectively reduce 47.5% of stimulated vibration. With the concept of the concentric spiral-flow channel, the developed CSF damper can achieve a wide range of dynamic ratio. The passive damping function provides the main damping effect by the viscous drag, and the active damping function realized the adjustable damping. By the utilization of GA-Fuzzy control, the semi-active vibration control can be effectively applied.