磁场作用下羰基铁粉磁流变液的剪切特性

Shear Performance of Magnetorheological Fluid of Carbonyl Iron Powder in Magnetic Field

使用流变仪在不同磁感应强度(0~0.86T)、不同剪切速率(100~1 000s^(-1))下测得羰基铁粉磁流变液的剪切应力和表观黏度,分析了其剪切性能,并通过拟合得到了剪切应力和磁感应强度的定量关系。结果表明:在相同的磁感应强度下,随着剪切速率的增加,该磁流变液的剪切应力缓慢增大,表观黏度成指数下降;该磁流变液的黏度变化符合Herschel-Bulkley模型,磁感应强度越大,其剪切稀化效应越明显;当磁感应强度分别在0~0.23T,0.45~0.65T范围内时,剪切应力和磁感应强度之间均存在指数关系,指数值分别为1.50,0.57,当磁感应强度在0.23~0.45T范围内时,剪切应力随磁感应强度的增加呈线性增大。

The shear stresses and apparent viscosities of the magnetorheological fluid （MRF） of carbonyl iron powder were measured by the rheomder under different magnetic flux densities （0-0.86 T） and different shear rates （100 1 000 s-1 ）. The shear performance of the MRF was analyzed and the quantitative relations between shear stress and magnetic flux density were fitted. The results show that the shear stress of the MRF increased slowly but the apparent viscosity decreased exponentially with the increase of the shear rate under the same magnetic flux density. The viscosity change of the MRF coincided well with the Herschel-Bulkley model, meaning that the larger the magnetic flux density, the stronger the shear thinning effect of the MRF. When the magnetic flux densities were in the range of 0-0.23 T and 0.45-0.6,5 T, the shear stress and magnetic flux density showed an exponential relationship and the index value was 1,50 and 0.57 respectively. While in the range of 0.23--0.45 T, the shear stress increased linearly with the increase of magnetic flux density.