Research of damper using electrorheological fluid

本研究提出了一种利用电流变或电流变磁流体的新型阻尼器。最初制备了几种类型的ER流体。以10nm的钛酸钡、数nm的钛酸钾晶须或10nm的蒙脱石作为分散相分散在绝缘油中。有些颗粒含有水分。当不含水分的蒙脱石颗粒分散在硅油中时，该流体非常稳定，价格便宜，电阻率高，并在外加电场作用下表现出较大的粘度增加。在2.5 kV/mm的电场下观察到1kPa左右的屈服应力。因此，在接下来的阻尼器实验中，主要使用这种流体。为了确定电流变流体的动态特性，采用机械阻尼装置进行了实验。识别方法是基于模型的最小二乘估计方法。采用线性积分滤波器直接从实验的离散时间数据中估计机械阻尼器设置的物理参数。结果表明，电场突变对电流变流体特性的响应时间延迟约为0.4秒。随后制备了几种ER磁流体。该流体受阻尼器内筒磁场梯度的吸引，能保持内筒自居中。而且这种流体可以通过磁力携带，因此，防止流体泄漏的密封是不必要的。将硅油基磁流体与电流变液混合制成的电流变磁流体用于阻尼器时，在谐振点处放大系数接近1，在任何位移处放大系数随频率升高而减小。该阻尼器将作为无源阻尼器应用，其行为类似于低通滤波器。

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.