薄壁构件精密加工柔性装夹用磁流变液剪切屈服应力研究

Research on Shear Yield Stress of Magnetorheological Fluid for Flexible Clamping of Thin-walled Components for Precision Machining

磁流变液剪切屈服应力是影响薄壁构件柔性装夹性能的重要指标,为提升磁流变液柔性夹具稳定可靠的装夹性能,通过试验对比方法,研究了添加剂、磁场强度、体积分数、温度等因素对水基和油基磁流变液剪切应力的影响。结果表明:对于油基磁流变液,硬脂酸添加剂能有效提高磁流变液的沉降性能;当磁场强度大于300mT时,硬脂酸添加剂使得磁流变液的剪切屈服应力有所下降;当磁场强度为600mT时,体积分数为40%的水基磁流变液的剪切屈服应力较油基磁流变液增大了37%;磁流变液的零磁场黏度和剪切应力与其体积分数呈正相关,磁场强度对磁流变液剪切应力的影响强于体积分数对磁流变液剪切应力的影响。体积分数为48%以上的油基磁流变液更适合用于薄壁构件的柔性夹具设计。

The shear yield stress of magnetorheological fluid is an important index affecting the flexible clamping performance of thin-walled components.In order to improve the stable and reliable clamping performance of the magnetorheological fluid flexible fixture,the effects of additives,magnetic field strength,volume fraction,temperature and other factors on the shear stress of water-based and oil-based magnetorheological fluids are investigated by experimental comparison method.The results are showed as following:for oil-based magnetorheological fluids,stearic acid additives can effectively improve the settling performance of magnetorheological fluids.When the magnetic field strength is greater than 300 mT,the stearic acid additive causes a decrease in the shear yield stress of the magnetorheological fluid.When the magnetic field strength is 600 mT,the shear yield stress of the water-based magnetorheological fluid with 40%volume fraction increases by 37%compared with that of the oil-based magnetorheological fluid.The zero-field viscosity and shear stress of the magnetorheological fluid are positively correlated with its volume fraction.The effect of magnetic field strength on the shear stress of magnetorheological fluid is stronger than the effect of volume fraction on the shear stress of magnetorheological fluid.The oil-based magnetorheological fluid with volume fraction of 48%and above is more suitable for the design of flexible fixtures for thin-walled components.