Research of damper using electrorheological fluid

本研究提出一种新型的电流变或电流变磁流体阻尼器。作为分散相，将10 nm的钛酸钡、几μ m的钛酸钾晶须或10 nm的蒙皂石分散在绝缘油中。一些颗粒含有水分。将不含水分的蒙脱石颗粒分散在硅油中，该流体稳定、廉价、电阻率高，并在电场作用下表现出较大的增粘作用。在2.5kV/mm的电场下，观察到约1 kPa的屈服应力。因此，在接下来的阻尼器实验中，主要使用这种液体。为了识别电流变液的动态特性，使用机械阻尼器装置进行了实验。辨识方法采用基于模型的最小二乘估计方法。利用线性积分滤波器直接从实验的离散时间数据中估计出机械阻尼器的物理参数。结果表明，电流变液的特性对电场突变的响应时间约为0.4秒。这种流体在阻尼器内筒内被磁场梯度吸引，使阻尼器内筒保持自定心。此外，这种流体可以通过磁力携带，因此，不需要密封以防止流体泄漏。将硅油基磁流体与电流变液混合制成电流变磁流体用于阻尼器时，在共振点处放大系数接近1，在任意位移处，放大系数随频率的增加而减小。该阻尼器将作为被动阻尼器应用，其表现类似于低通滤波器。

This research presented a new type of damper using electro-rheological (ER) or ER magnetic fluid.Initially serveral types of ER fluid were prepared. As the dispersed phase, 10nm of barium titanate, several mum of potassium titanate whisker or 10nm of smectite were dispersed in insulated oil. Some particles were included moisture. When smecite particles containing no moisture were dispersed in silicone oil, this fluid was very stable, cheap, high electric resistivity and showed large viscosity increase by applying electric field. Yield stress of about 1kPa was observed at 2.5 kV/mm electric fieldd. Therefore, in the following experiment of damper this fluid was mainly used.In order to identify dynamic characteristics of ER fluid an experiment was carried out using mechanical damper setup. The identification method was model-based one with least-squares estimation technique. A linear integral filter was used to estimate physical parameters of the mechanical damper setup directly from the discrete time data of the experiments. It was shown that the time delay for characteristics of the ER fluid corresponding to a sudden change of electric field was about 0.4 seconds.Next several ER magnetic fluid was prepared. This fluid attracted by magnetic field gradient in the inner cylinder of damper could keep self-centeredly the inner cylinder. Also this fluid could be carried by magnetic force, therefore, the sealing to prevent the leakage of fluid was not necessary. When ER magnetic fluid produced by mixing silicone oil based magnetic fluid and ER fluid was used in damper, the magnification factor approached 1 at resonance point and decreased at higher frequency at any displacement. This damper would be applied as a passive damper behaving like a low-pass filter.