磁场作用下磁流变液剪切性能的实验分析

本文研究了磁流变液的力学性能,制备了羰基铁粉体积分数为20%的硅油基磁流变液,观察了磁流变液在磁场作用下的微观变化,测试了磁流变液的剪切性能。实验表明,无磁场作用下,磁流变液为牛顿流体;在磁场作用下,随着剪切速率的增加,剪切应力趋于稳定,表观粘度呈现指数式下降,磁流变液具有剪切稀化效应,符合广义Bingham模型。磁流变液剪切应力和外加电流的依赖关系为:在电流较小时,剪切应力表现为指数增长,指数值约为1.5;随着外加电流的增大,剪切应力表现为线性增长,最终达到稳定值。

Experimental Analysis on Shear Properties of Magnetorheological Fluids under Magnetic Fields

Mechanical properties of magnetorheological fluids (MRFs) were studied.Silicone-basedMRFs were prepared with 20％ volume fraction of carbonyl iron powder.The Keyence VHX-600 super depth 3D digital microscope was used to observe the microscopic movement of MRFs under magnetic fields.Rheometer Physica MCR 301 was used to test shear properties of MRFs.The experimental results show that MRFs are Newtonian fluids without magnetic field.Shear stress of MRFs remains stable but apparent viscosity decreases exponentially with the increase of shear rate under magnetic fields.MRFs are shear thinning of Bingham fluids in the presence of magnetic field and conform to the generalized Bingham model.Shear stress increases also exponentially with the index value is about 1.5 when the external current is low.With the increase of external current,shear stress increases at a linear trend and eventually reaches a stable value.