硅树脂基磁流变胶流变特性研究及Herschel-Bulkley模型参数识别

为了探究硅树脂基质磁流变胶的流变特性,自行制备了羰基铁粉质量分数分别为30%、50%、70%的三种磁流变胶MRG-30、MRG-50、MRG-70,并对其展开稳态旋转剪切测试和动态振荡剪切测试.结果表明:剪切应力随磁场变化分为快速增长、缓慢增长、饱和三个阶段,羰基铁粉含量对零场粘度、剪切应力、响应速率影响较大,MRG-70磁流变效应最好;磁流变胶的流动特性符合Herschel-Bulkley函数变化规律,且非牛顿指数n都满足n1,具有剪切稀化特性;线性粘弹性区域临界应变幅值rLVE随着磁感应强度增强而增大,磁流变胶的储能模量对频率的依赖性微弱;法向应力随着磁感应强度增强而增大,但频率对材料的法向应力的影响十分微弱.

Study on Rheological Properties of Magnetorheological Gel Based on Silicone and Parameter Identification of Herschel-Bulkley Model

In order to study the rheological properties of magnetorheological gel(MRG) based on silicone, three kinds of MRGs named MRG-30, MRG-50, MRG-70 were prepared based on carbonyl iron powder with a mass fraction of 30%, 50%, 70%, respectively. The steady state rotation shear and dynamic oscillation were systematically tested. The results show that the shear stress varies with the magnetic field and can be classified into three stages: rapid growth, slow growth and saturation. The content of carbonyl iron powder has a great influence on the zero-field viscosity, shear stress and response rate, and MRG-70 has the best magnetorheological effect. The flow characteristic of MRG is consistent with the Herschel-Bulkley function, and the non-Newtonian exponent n satisfies that n<1 with shear thinning property. The critical strain amplitude of linear viscoelastic region increases with the enhancement of the magnetic field, and the storage modulus of the MRG is weakly dependent on the frequency. Normal stress increases with the increase of magnetic field, but the influence of frequency on the normal stress of MRG is very weak.