磁性奈米流體流變特性與減震消能之分析

Analysis of magnetic nanofluid rheological properties and vibration energy dissipation

陳韋帆(Wei-Fan Chen)

指導教授 ： 翁輝竹

中原大學/工學院/機械工程研究所/碩士(2018年)

https://doi.org/10.6840/cycu201800412

摘要

磁流變流體之研究係考慮微米粒子以探討流體流變特性，而本論文考慮流體內具磁性奈米粒子(磁性奈米流體)以完成其流變特性與減震消能之分析，目的在探討外部磁場與奈米粒子體積分率對磁性奈米流體之流變特性與減震消能之影響。首先，利用化學共沉法與溶膠凝膠法製備水基磁性奈米流體。接著，完成外部磁場，以及黏度與阻尼測試系統之架設。最後依據實驗數據探討磁性奈米流體之流變特性與減震消能之效應。
研究結果發現，在流變特性方面，磁性奈米流體在奈米粒子體積分率大於約3%至3.5%時，流體之流變特性會明顯由傳統的牛頓流體逐漸轉變為非牛頓流體之剪厚流體，同時有賓漢材料之降伏應力現象出現，且流體之剪厚效應及降伏強度皆會隨著奈米粒子體積分率與磁場強度的增加而增加。在減震消能方面，流體之阻尼力隨著奈米粒子體積分率及磁場強度增加而上升，使得阻尼測試系統之受力最大值大幅降低。在本研究所探討的參數範圍內，其降低幅度最多可達30.3%，而阻尼測試系統之安定時間下降幅度最多可達83%。

關鍵字

磁性奈米材料，磁流變特性，減震消能，粒子體積分率，均勻磁場

並列摘要

The study of magnetorheological fluids mainly consider microparticles to investigate the rheological properties of fluids. This thesis, however, considers fluids with magnetic nanoparticles (magnetic nanofluids) to conduct an analysis of their rheological properties and vibration energy dissipation. The purpose is to investigate the influences of external magnetic field and nanoparticle volume fraction on the rheological properties and damping energy dissipation of magnetic nanofluids. First, the chemical preparation of water-based magnetic nanofluids was completed by the chemical coprecipitation method and the sol-gel process. Further, the external magnetic field, and the viscosity as well as the damping test system were set up. Finally, the effects of rheological properties and damping energy dissipation of magnetic nanofluids were examined according to the experimental data.
Experimental results revealed that for the rheological properties, the fluid flow behavior gradually changes from classical Newtonian behavior to non-Newtonian shear thickening behavior when the nanoparticle volume fraction is greater than about 3% to 3.5%, at the same time, the yield-stress phenomenon of Bingham materials could be found. Both the shear thickening effect and the yield stress strength of fluids could increase with the increases of the nanoparticle volume fraction and magnetic field strength. As for the vibration energy dissipation, the damping force of fluids increases with the increases of the nanoparticle volume fraction and magnetic field strength, making the peak force of the damping test system greatly reduced. Under the ranges of parameters studied, the peak force could be reduced by up to 30.3%, and the settling time of the damping test system could be reduced by up to 83%.

並列關鍵字

magnetic nanomaterial ； magnetorheological property ； vibration energy dissipation ； particle concentration ； uniform magnetic field

參考文獻

Bagheli, S., Khandan, F. H., Lotfi, O. R., and Ghaemi, M., 2015, “Synthesis and experimental investigation of the electrical conductivity of water based magnetite nanofluids,” Powder Technology, 274, 426–430.

Chandrasekar, M., Suresh, S., and Chandra, B. A., 2010, “Experimental investigations and theoretical determination of thermal conductivity and viscosity of Al2O3/water nanofluid,” Experimental Thermal and Fluid Science, 34, 210–216.

Chiam, H. W., Azmi, W. H., Usri, Rizalman, M. N. A., and Adama, N. M., 2017, “Thermal conductivity and viscosity of Al2O3 nanofluids for different based ratio of water and ethylene glycol mixture,” Experimental Thermal and Fluid Science, 81, 420–429.

Den Hartog, J. P., 1956, Mechanical Vibrations, McGraw-Hill, New York.

Forero-Sandoval, I. Y., Vega-Flick, A., Alvarado-Gil, J. J., and Medina-Esquivel, R. A., 2017, “Study of thermal conductivity of magnetorheological fluids using the thermalwave resonant cavity and its relationship with the viscosity,” Smart Materials and Structures, 26, 025010.