Research of damper using electrorheological fluid

本研究提出了一种新型的电流变液阻尼器，并初步制备了几种不同类型的电流变液。作为分散相，在绝缘油中分散了10 nm的钛酸钡、几个微米的钛酸钾晶须或10 nm的蒙脱石。一些颗粒中含有水分。将不含水分的蒙脱石颗粒分散在硅油中，该油液稳定性好、成本低、电阻率高，在外加电场的作用下表现出较大的增粘效果。在2.5千伏/毫米电场下，测得屈服应力约为1kPa.为了识别电流变流体的动态特性，采用机械阻尼器装置进行了实验研究。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试验的离散时间数据中估计机械阻尼器装置的物理参数。结果表明，电流变液体的特性对应于电场突变的时延约为0.4秒。阻尼器内筒中的磁场梯度吸引了这种流体，使其保持在内筒的自定心状态。此外，这种液体也可以通过磁力携带，因此不需要密封以防止液体泄漏。将硅油基磁性液体和电流变液体混合制成的电流变磁液用于阻尼器时，在共振点放大系数接近1，在任意位移下，放大系数在较高频率处减小。这种阻尼器将被用作被动阻尼器，其作用类似于低通滤波器。

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.